Filter cartridges; features and methods of assembly; air cleaner assemblies; and, filter cartridge combinations

ABSTRACT

Filter cartridge arrangements, features thereof and assembly for use therewith, are provided. Selected filter cartridge features disclosed are particularly well adapted for use with a safety or secondary filter cartridge, usable with media thereof projecting into an open interior of a main filter cartridge, in use. An example filter cartridge is described, with a non-pleated end and a pleated end, although variations are also described. Advantageous main cartridges are also described. Methods of assembly and systems for use are described.

CROSS-REFERENCE TO RELATED APPLICATION

The above referenced application includes with edits, the disclosure ofU.S. Ser. No. 61/731,259, filed Nov. 29, 2012. The complete disclosureof U.S. Ser. No. 61/731,259 is incorporated herein by reference. A claimof priority to U.S. Ser. No. 61/731,259 is made to the extentappropriate.

FIELD OF THE DISCLOSURE

The present disclosure relates to filter cartridges, features andtechniques. Example features and techniques described are configured tobe particularly convenient as, or for use with, secondary or safetyfilter cartridges for air or other gas filter arrangements andassemblies. Advantageous main filter cartridges are also described.Preferred features of selected filter cartridges and methods of assemblyare described.

BACKGROUND

Gas filters are used in a variety of assemblies and systems. Forexample, it is desirable to filter intake air to a variety of vehiclesand other equipment. Typically, the intake air is combustion air for aninternal combustion engine, often a diesel engine. Filtration isgenerally conducted with a gas (air) cleaner assembly (i.e. a filterassembly) typically including a housing and an internally positionedfilter cartridge arrangement. The filter cartridge arrangement typicallyincludes a main filter cartridge, through which the air is passed andwhich is operated with deposition of particulate material carriedtherein onto filter media of the main filter cartridge. In a variety ofair cleaner assemblies, the main filter cartridge and the remainder ofthe assembly are configured for out-to-in flow during filtering, inreference to direction of air flow through the media of the main filtercartridge, during normal operation. When this is the case, the media ofthe main filter cartridge is typically configured surrounding an openfilter interior that is a clean air side of the media.

In many instances, a safety or secondary filter cartridge is includedwithin the filter assembly. When a safety or secondary filter cartridgeis used with an assembly configured for out-to-in flow during filtering,the safety filter is typically configured with media thereof surroundingan open filter interior and projecting into an open filter (clean gas)interior of the main filter cartridge. Thus, after the gases (air) passthrough the media of the main filter cartridge, the gases (air) passthrough the media of the safety filter cartridge as those gases (air)are directed toward an outlet from the air cleaner.

In a typical assembly, both the main filter cartridge and the safetyfilter cartridge are configured as service components. That is, they areconfigured to be removable from, and to be replaceable within, the aircleaner assembly. As a result, each is generally provided with areleasable housing seal, i.e., a seal which removably seals to a portionof the housing or air cleaner assembly, when the two filter cartridgesare properly and operably positioned. Such seals are sometimes referredto as “releasable seals” since they can be established and be removedwithout damage to the cartridges or housing component(s) engaged.

A variety of assemblies have been developed which can use such generalarrangements. Examples are described in WO 2009/014986 A1 and WO2012/116314 A1, each which is incorporated herein by reference and whichare owned by the owner of the present disclosure, Donaldson Co., Inc.,of Bloomington Minn.

Issues relating to the safety or secondary filter cartridgeconfiguration concern limitations in its size and shape imposed by therequirements of the gas filter assembly for location of the safetyfilter, typically enclosed within the main filter cartridge yet stillmeant to be removably sealed to a feature of the air cleaner assembly orhousing; and the preferred desire to be able to service the main filterwithout dislodging the safety. Improvements have been sought.

SUMMARY

According to the present disclosure, features relating to filtercartridges, especially ones well adapted for use as, for use with,secondary or safety filter cartridges, are provided. Also methods ofassembly and use are provided, as well as combinations of gas filterfeatures and filter cartridge features.

According to one aspect of the present disclosure, a filter cartridge,typically to be used as a secondary or safety filter cartridge by beingpositioned with media thereof oriented projecting into an open interiorof a main filter cartridge, is provided. The safety or secondary filtercartridge comprises an extension of media, typically surrounding an openfilter interior and having a first end and the second end. In preferredconfigurations, at the first end, the media either: has no pleats; or,if pleated, preferably has no pleats greater than about 3 millimeters indepth, more preferably no greater than 2 mm in depth. However, at thesecond end, in most preferred applications, the media is pleated, with apleat depth of at least 5 mm, typically at least 10 mm and often atleast 15 mm.

This overall media and pleat configuration can be provided in a filtercartridge with a variety of additional features, to substantialadvantage, as discussed below. In addition, it allows for anadvantageous combination with main filter cartridge features and/orfilter assembly features generally.

According to an alternate aspect of the present disclosure, somefeatures and techniques usable in a media support one safety cartridge,for advantageously securing a filter cartridge in place, especially asecondary safety filter cartridge, are discussed and described. Thesecan be used in combination with the preferred pleat feature(s)identified above, or in alternate configurations as desired. In anexample depicted, an end of the cartridge includes an aperturetherethrough, which is lined by a cushion and/or seal member. Thehousing can include structure that projects into engagement with thecushion and/or seal member, to advantage.

Also, herein selected advantageous structural features, for examplemedia support features, for preferred filter cartridges are described.These can be used in association with the various features describedpreviously in this section, or independently, to advantage.

Methods of assembling a filter cartridge in accord with the featuresdescribed herein are also provided. The methods can be used toadvantage, to achieve a desirable filter cartridge in an efficientmanner.

Also according to the present disclosure, filter assemblies, includingfeatures specifically and advantageously configured for use withpreferred filter cartridges are described herein are shown anddescribed. Also main or primary filter cartridge configurations thatparticularly well adapted for use with components as characterizedherein are described.

There is no specific requirement that a filter cartridge or componentinclude all of the features specifically characterized herein, or evenas specifically characterized above in this section, in order to obtainsome benefit according to the present disclosure. Further, there is nospecific requirement that the features described in the context of asafety or secondary filter cartridge, only be implemented in a safetyfilter cartridge, as opposed to an alternate filter cartridge, unlessotherwise specifically recited. In addition, while the techniques aredescribed in connection with air filtration, they can be applied inother types of gas filters or in filtering of other media. It is noted,however, that the techniques were particularly developed for, and areparticularly advantageous for, air filter applications, especially theseinvolving a secondary or safety filter cartridge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a filter cartridgeaccording to the present disclosure; the view being taken generallyalong line 1-1, FIG. 2.

FIG. 1A is an enlarged, fragmentary, schematic view of a firstidentified portion of FIG. 1.

FIG. 1B is an enlarged, fragmentary, schematic view of a secondidentified portion of FIG. 1.

FIG. 1C is a schematic cross-sectional view analogous to FIG. 1, showingsome optional variations in the filter cartridge of FIG. 1D.

FIG. 1D is an enlarged fragmentary schematic view of an identifiedportion of FIG. 1C.

FIG. 1E is an enlarged fragmentary schematic view of an identifiedportion of FIG. 1C.

FIG. 2 is a schematic enlarged end view of the filter cartridge of FIG.1; the view being taken toward a top end in the view/orientation of FIG.1.

FIG. 2A is a view analogous to FIG. 2, but of the cartridge as depictedin FIG. 1C.

FIG. 3 is a schematic, enlarged, second end view of the filter cartridgeof FIG. 1; the view of FIG. 3 being taken toward the bottom end of theview/orientation of FIG. 1.

FIG. 4 is a schematic exploded view of the filter cartridge of FIG. 1.

FIG. 5 is a schematic perspective view of a frame piece component of thecartridge of FIG. 1.

FIG. 6 is a schematic end view of the frame piece of FIG. 5; the view ofFIG. 6 being taken toward the top end of the view/orientation of FIG. 5.

FIG. 7 is a schematic cross-sectional view of the frame piece of FIG. 5,taken generally along line 7-7, of FIG. 6.

FIG. 8 is a schematic perspective view of a filter media component ofthe filter cartridge of FIG. 1.

FIG. 9 is a schematic end view of the filter media component of FIG. 8;the view of FIG. 9 being taken toward the top end of theview/orientation of FIG. 8.

FIG. 9A is a view generally analogous to FIG. 9, with selecteddimensions indicated.

FIG. 10 is a schematic side elevational view of the media component ofFIG. 8.

FIG. 11 is a schematic cross-sectional view of an example housing foruse in an air cleaner assembly that can include a cartridge according toFIGS. 1-10, according to the present disclosure.

FIG. 11A is a schematic enlarged fragmentary view of a selected portionof FIG. 11.

FIG. 11B is an enlarged fragmentary schematic view of a second selectedportion of FIG. 11.

FIG. 12 is a schematic cross-sectional view of a housing of a filterassembly according to the present disclosure, having a safety cartridgein general accord with FIGS. 1-10 installed therein.

FIG. 12A is an enlarged fragmentary schematic view of a selected portionof FIG. 12.

FIG. 12B is an enlarged fragmentary schematic view of a selected portionof FIG. 12.

FIG. 12C is a schematic view generally analogous to FIG. 12, withselected dimensions indicated.

FIG. 13 is a schematic cross-sectional view of an air cleaner assemblyaccording to the present disclosure having a main filter cartridgetherein and a safety filter cartridge in accord with FIGS. 1-10installed therein.

FIG. 13A is an enlarged schematic fragmentary view of an identifiedportion of FIG. 13

FIG. 13B is an enlarged fragmentary schematic view of a secondidentified portion of FIG. 13.

FIG. 14 is a schematic cross-sectional view of an alternate housing tothe housing depicted in FIG. 11, usable in accord with the principles ofthe present disclosure.

FIG. 15 is a schematic cross-sectional view of an alternate main filtercartridge, to the cartridge depicted in FIG. 13 and usable inarrangements according to the present disclosure.

DETAILED DESCRIPTION I. An Improved Secondary or Safety Filter CartridgeGenerally, FIGS. 1-10.

A. Further Regarding Safety or Secondary Cartridge Use in FilterAssemblies Generally; Some Selected Issues of Concern

As indicated previously, in general the present disclosure relates tofeatures and techniques that are specifically adapted for advantageoususe in secondary or safety filter cartridge arrangements and assemblies;although the techniques can be applied in other applications. Thetechniques are understandable, for example, in the context of use in anair cleaner assembly, such as ones having features as generallydescribed in WO 2009/014986A1 or WO 2012/116314 A1, incorporated hereinby reference.

In general, such filter assemblies comprise an air cleaner housing and aprimary or main filter cartridge. The main filter cartridge typicallycomprises media surrounding an open filter interior. The assembly istypically configured for “out-to-in” flow during filtering, with respectto gas (air) flow direction through the media of the main filtercartridge. By the term “out-to-in” flow in this context, it is meantthat the flow during filtering through the media of the main filtercartridge is generally: from a region outside of the cartridge, throughthe main cartridge media, to the open filter interior of the maincartridge surrounded by media. Thus, the open filter interior of themain filter cartridge is a clean air region.

The main filter cartridge is positioned to be loaded with contaminantthereon during use, and is, as a result, typically constructed as aserviceable component. Thus, the housing is typically configured with amain housing body or base section and an access cover, the access covercomprising a serviceable cover removable for internal servicing. Themain filter cartridge is typically configured to be removably installedwithin the housing interior. To accomplish this, the main filtercartridge has a releasable housing seal. By “releasable”, in thiscontext, it is meant that the seal is established by the main cartridgeengaging a selected portion of the housing (or assembly) when thecartridge is installed, and the seal is readily removed and releasedwhen the cartridge is removed from the housing. Such “releasable” sealsare capable of being separated or removed without damage to either themain filter cartridge or the housing.

Many features concerning main filter cartridge configuration, relate to:ensuring a desirable amount of filter media surface area available forload, given limitations on volume, etc.; ensuring that the housing sealis configured so that the seal is properly established and maintained;and, ensuring that the cartridge cannot be misinstalled and/or that analternate, inappropriate, cartridge cannot be inadvertently installed inthe system. A variety of constructions have been developed to addressthese issues, including the general ones described in WO 2009/014986 A1and/or WO 2012/116314 A1.

A housing, for example of an air cleaner assembly, is typically providedwith an outlet air (gas) conduit or tube, in communication with openinterior of the main filter cartridge. Thus, the housing seal on themain filter cartridge is typically either sealed to the outlet flowtube, or to a portion of the housing that surrounds a volume with whichthe outlet flow conduit or tube communicates. Herein, the portion of theair cleaner assembly to which the seal of the main cartridge releaseablyengages, will be referred to as a portion of the housing, whether it isan outlet separable from a remainder of the housing structure, or somestructure integral with other portions of the housing structure.

In many systems, it is desirable to provide the air cleaner assemblywith a serviceable safety or secondary filter cartridge. The safety orsecondary cartridge is typically positioned in the air (gas) flow pathbetween the main filter cartridge, and the outlet flow exit of filteredair (gas) from the filter assembly (housing). When the main filtercartridge is configured for “out-to-in flow” during filtering, thismeans that the safety or secondary cartridge is typically positionedwith at least a portion thereof oriented within the main filtercartridge interior.

Herein, the terms “secondary” or “safety” when used in reference to afilter cartridge positioned with media downstream of the main filtercartridge, are meant to be used interchangeably and withoutdifferentiated meaning.

Preferably, the safety filter cartridge is a serviceable componentindependent of the main filter cartridge. This means: that the mainfilter cartridge can be installed in, and be removed from, the housing,without removing (and preferably without dislodging from propermounting) the safety cartridge; and, that servicing the main filtercartridge does not necessarily require servicing the safety filtercartridge.

Independent main and safety cartridges are advantageous for a number ofreasons. An advantage, is that when the main cartridge is serviced, thesafety cartridge can be left in place so as to avoid dirt and dust fromentering the clean gas (air) plenum of the gas (air) cleaner system, forexample as an interior of the housing is cleaned. Other advantagesrelate to convenience of installation and assembly, as well asconvenience of component manufacture. In addition, separate constructionallows for efficient material usage and disposition, especially sincethe main filter cartridge may need to be serviced, or be removed forinspection, more often than the safety cartridge.

There are a number of issues relating to safety or secondary filtercartridge configuration and assembly. For example, in many air cleanerassemblies, there is little option available for location of sealingbetween the housing and the safety filter cartridge. One regionsometimes available, is an interior (or exterior) of a flange or tubularsurface that surrounds a gas exit flow from the housing. This could, forexample, comprise a surface of an outlet flow tube, or it could comprisea surface of a flange that projects into the housing at a locationsurrounding, but spaced from, the outlet flow tube.

When a cartridge seals to such a flange or tube, the seal is sometimesreferenced as “radially” directed. By this, it is meant that the sealforces are generally directed around a central axis, with the forces ofsealing being generally directed toward or away from that central axis.Typically, the central axis referenced, is an axis through an air flowexit from the associated cartridge, typically an axis surrounded by themedia. A seal may be referred to as “radially outwardly directed” and bysimilar terms, if the seal engages a housing component that surroundsthe seal during use; and, the seal may be generally characterized as“radially inwardly directed” or by similar terms, when the seal isconfigured to surround and engage the housing component in use.

An issue with radially directed seals, is that they can take-up radialdimension within the housing. This reduces the cross-sectional areaavailable for gas flow exiting the cartridge and/or housing, and canundesirably add to restriction.

Of course, the housing in which the safety cartridge is used can be madesufficiently large to minimize this problem, but there are limitationsimposed on this by: a preference for the main filter cartridge to haveas much surface area and media volume as reasonably possible; apreference that the air cleaner be as small and light as reasonablypossible; cost and material issues; and, issues with handling andshipping components.

The restriction issue presented by reduction in cross-sectional areadefined by the safety cartridge for air flow, as characterized in thissection, relates to the dimension of radial direction (width) of thesecondary or safety filter cartridge toward a central axis, from theseal surface, i.e. the part of the radial seal positioned to sealinglyengage the housing. In general, it is desired that this amount of radialwidth or extension of the safety cartridge structure be maintained assmall as reasonably possible, so as to ensure that the outlet flowcross-sectional size, through an end of the safety filter cartridge andto the outlet from the housing, remains as large as reasonably possible.

A variety of techniques have been implemented to manage this issue withthe safety cartridge. An example depicted in WO 2012/116314, includesconfiguring the safety cartridge from non-pleated media, so as to limitthe amount of radial dimension taken up by the media. Such techniqueshave been applied in a wide variety of safety filter or secondary filterelement configurations.

However, there are issues presented from using non-pleated media. Inparticular, it limits the amount of media surface area in a safetyfilter available for filtering. In general terms, the surface area ofmedia available in the filter cartridge is preferably as large asreasonable for the volume available. This renders advantageous mediaface velocities. Media face velocity is generally the gas flow ratethrough the media divided by upstream surface area of the media. Smallermedia surfaces lead to higher face velocities. Higher face velocitiesare typically less desirable than lower face velocities for a number ofreasons. For example, higher face velocities generally result in agreater restriction placed on air flow through the air cleaner assembly,which is undesirable with respect to equipment operation and filterlifetime. Also, the higher the face velocity, the more likely a particlecan penetrate through the media and reach the clean air (gas) plenum.

It can be understood that non-pleated media of a given outer perimetersize has a higher face velocity than pleated media which defines thesame outer perimeter size (i.e., outer perimeter size disregarding pleatpresence). However, introduction of pleats into the media has generallybeen undesired for certain secondary filters, as pleats introduce radialwidth dimension to the cartridge, which leads to increase in restrictionto gas flow outwardly from the cartridge and assembly. Herein in thenext section, the filter cartridge features are described, which can beapplied to balance these issues to advantage.

In addition, especially with a safety cartridge that projects into theopen interior of the main cartridge during use, gas flow exiting themain cartridge and being directed toward the gas flow outlet can beaffected by the shape features of the secondary cartridge. Advantageousshape features are discussed in the next section, which can lead to moredesirable flow characteristics. This can help limit restriction increaseand provide more desired filter assembly operation.

The issues of limited surface area available for secondary or safetyfilter systems are exacerbated, when the main filter cartridge tapersdownwardly in extension from an exit end toward a remote end of thecartridge. This is because the inward tapering of the main filtercartridge reduces cross-sectional area into which the safety filter canproject, adjacent an end of the main filter cartridge remote from theair flow exit. Techniques described herein can be applied advantageouslyto manage such issues, in a variety of systems.

B. An Example Filter Media Configuration FIGS. 1-10.

The reference numeral 1, FIG. 1, generally depicts a filter cartridge inaccord with the present disclosure. The example filter cartridge 1depicted, is configured with features advantageous for use in a safetyor secondary filter cartridge, for example to be used in an assemblyconfigured for out-to-in flow through a main filter cartridge duringoperation; and, in which the secondary filter cartridge is configured tobe sealed radially to a surface of a housing component tube or (flange),with a media of the safety filter cartridge projecting into an openfilter interior of a main cartridge. It will be understood that theselected advantageous features described herein, however, can be appliedin a variety of alternate applications/configurations.

Referring to FIG. 1, the filter cartridge 1 depicted comprises anextension 2 e of media 2 extending between first and second media ends3, 4. In general terms, the media 2 surrounds a central axis X anddefines an open interior 2 i, which corresponds to a clean gas (air)side of the media 2.

The first media end 3 is positioned at an exit end for filter and gases,from the filter cartridge 1. That is, end 3 of the media corresponds toan open exit flow end 7 of the filter cartridge 1, for filtered gasesflow during use. It is in regions adjacent end 7 that it is mostdesirable that the filter cartridge 1 maintain a relatively small radial(width) dimension, so as to avoid increasing restriction to gas flowexit, to an extent reasonable.

To provide for the advantageous opening 7, preferably media 2, at end 3,is non-pleated or minimally pleated. By “minimally pleated” in itscontext, it is meant that if there is any pleat definition at end 3 atall, it is no more than 3 mm in pleat depth. Preferably, any such pleatdefinition is with a pleat depth of no more than 2 mm and morepreferably no more than 1 mm. By “pleat depth” in its context, referenceis meant to a dimension of a pleat radially inwardly from an outermostperimeter, in a direction toward central axis X. Most preferably at end3, the media 2 is not pleated at all, i.e. it has no pleat depth.

However, as explained above, it is desirable to provide the media 2 witha surface velocity as low as reasonable. Thus, it is desired for themedia 2 to have a pleated configuration in spite of the fact that it isdesirable to have minimal or no pleat depth at end 3. To accommodatethis, the media 2 is provided with a pleat definition adjacent secondend 4. Preferably the pleat definition is one that decreases in pleatdepth in a direction of pleat extension from end 4 toward end 3. Such apleat is shown in FIG. 1, for example, at 10, with a pleat depth at end4 being at least 5 mm, preferably at least 10 mm, often at least 15 mm,and in many instances 20 mm or more. Indeed, for a typical application,a pleat depth at end 4, (i.e. at the second end of the media), on theorder of 15-40 mm is typical, although alternatives are possible. Thiscan be used to provide a media area at least 10%, typically at least20%, and often 25% or more, greater than a media area if non-pleatedmedia of the some outer perimeter size, is used.

In general terms, adjacent the second end 4, the media 2 is pleated,comprising a plurality of pleats having a pleat depth of at least 5 mmand preferably as defined. Herein, when it is said that a “plurality ofpleats” has this definition, it is not meant that every pleat adjacentthe end 4 must have this definition, but merely that there be a set orplurality of them of that does. In a typical example as depicted,however, every pleat adjacent end 4 has a pleat depth in accord with thecharacterizations of the previous paragraph, to achieve preferable mediaarea increase.

An example media configuration depicted to provide for this definition,can be understood by reference to FIG. 8. Referring to FIG. 8, the media2 is depicted surrounding axis X and in extension between first, in theexample non-pleated (or minimally pleated) end 3, and, opposite, second,end 4. The second end 4 comprises a plurality of inwardly directed(inner) pleats 10 and a plurality of outwardly directed (outer) pleats11; the inner pleats 10 and outer pleats 11, alternating. In a typicalapplication of the principles according to the present disclosure, media2 will comprise at least 5 each of inner pleats 10 and at least 5 suchouter pleats 11, and typically not more than about 15 of each. A typicalnumber will be within the range of about 6-12 inclusive, althoughalternatives are possible.

The techniques described herein can be applied with an alternate numberof pleats, and the number of pleats is not critical to obtain someadvantage. However, relatively few pleats (12 or less) that haverelatively wide pleat definitions facing radially outwardly, i.e. alongthe outer perimeter, can be advantageous for desirable gas flowcharacteristics and avoidance of undesirable gas flow restriction.

Referring to FIGS. 9 and 9A, views taken toward media end 4, typically,the outer pleats 11 will have a generally wide, rounded, as opposed tosharp, pleat tip definition, for example, defining a radius at end 4 foreach pleat 11 of at least 3 mm, typically at least 4 mm, for exampletypically 4-11 mm, inclusive. This will be advantageous with respect toformation of the configuration, although alternatives are possible. Theinner pleats 10, however, will typically be formed more sharp and to asmaller radius of curvature. A typical radius for the inner pleat tipswould be no larger than 3 mm and often no larger than 2 mm.

As indicated, the outer pleats 11 are typically and preferablyrelatively wide. By this, it is meant that the opposite sides 11 a, 11b, FIG. 9, of the pleats 11, adjacent end 4, generally diverge from oneanother at an angle of at least 10°, typically at least 15°, for examplein the order of 15-30°, inclusive; and/or the pleat sides 11 a, 11 breach a distance apart from one another of at least 8 mm, usually atleast 10 mm and often 10-20 mm, within a selected distance from theoutermost pleat tip 11 t of no greater than about 15 mm.

The relatively wide, rounded, outer tips 11 t of the outer pleats 11provides for a large outside surface area for engagement with supportstructure, as discussed below. It is desirable to avoid a sharp point atpleat tips 11 t, at least for that reason. The relatively sharp internalpleats 10 t provide for convenient assembly and manufacturing, as wellas desirable media characteristics and flow characteristics.

Referring to FIG. 9, it is noted that the outer pleat tips 11 t,adjacent end 4, are angularly spaced rather widely, with spacing (oncenter) being on the order of at least 30°, typically 30-50°, inclusive,(usually 35°-50°, inclusive) around central axis X. The dimension ofthis spacing (outer pleat tip 11 t to outer pleat tip 11 t) is typicallyat least 20 mm, usually at least 30 mm, for example 35 mm to 55 mm,inclusive. Also, the inner pleat tips, adjacent end 4, are spaced ratherwidely, typically at least 30° often at least 35° and usually in theorder of 35°-50°, inclusive. This creates long, wide flow channels onthe exterior 11 c and on the interior 10 c, along which gases can flowtoward the outlet end 3. This provides an arrangement that is desirablewith respect to management of gas flow restriction issues, and is areason why it is desired to not have an excessive number of pleats(greater than 12, and typically 10 or less) in spite of the advantagesfrom increased surface area and lower face velocity.

In FIG. 9A, some example dimensions are provided as follows: ZX=1.5 mmradius; ZY=8 mm radius; ZW=124.7 mm diameter; ZC=2 mm; YA=119 mm; and,YB=124.7 mm.

In FIG. 10, example dimensions are as follows: AE=379 mm; AF=124.7 mm.

C. Media Support and Filter Cartridge Features; FIGS. 1-7

Typically, the outermost tips 11 t of outer pleats 11 and innermost tips10 t of a plurality of the pleats 10 will extend generally straight, inextension from end 4 in a direction toward end 3. Typically, the outerpleat tips 11 t will either extend parallel to central axis X, or at anacute angle of no less than 88° and typically no less than 89° withrespect to a plane perpendicular to central axis X. Typically, the pleattips 11 t of a plurality of pleats 11 extend at an angle relative to aplane perpendicular central axis X of about 88-90°, inclusive.

A plurality of inner pleat tips 10 t, typically extend radiallyoutwardly from central axis X substantially, and extend at an acuteangle of no greater than 88°, typically no greater than 87° and oftenwithin the range of 75°-86°, inclusive, relative to a planeperpendicular to central axis X; with the extension being radiallyoutward in extension from adjacent end 4 in a direction toward end 3.

Typically, an angle (acute angle) of extension of the plurality of outerpleat tips 11 t (relative to a plane perpendicular to central cartridgeaxis X in a direction of extension from end 4 toward end 3) is at least1° larger, typically at least 2° larger and often at least 4° larger,than an analogous acute angle of extension of the plurality of innerpleat tips 10 t relative to the same plane perpendicular to the centralcartridge axis X and also in extension from adjacent end 4 in adirection toward end 3. Typically, end 22 is an end of the media support20 engaged by end 4 of the media. End 21 is an end remote from end 22,in the direction of cartridge end 7 and media end 3. The end 21 willtypically be positioned closer to media end 3 than to media end 4, andtypically within 50 mm of end 3, usually within 40 mm of end 3, mostoften within 20 mm of end 3 and in many instances, within 10 mm of end3. In some instances, end 21 may be positioned at media end 3, but inthe example depicted, end 21 is recessed toward media end 4, slightly,from media end 3, as discussed below.

In FIG. 10, a side view of the media 2 in the configuration of FIG. 8 isshown. In FIG. 10, example dimensions are indicated as follows: AE=379mm; AF=124.7 mm. Of course the principles can be implemented in avariety of different sizes and different arrangements.

In the particular cartridge 1 depicted, FIG. 1, the media 2 is supportedby a frame arrangement 20, referenced generally as a media support. Themedia support 20 generally extends between media support first andsecond ends 21 and 22. Preferably, the media support adds relativelyminimally to the radial thickness or dimension of cartridge 1, near end7. Near end 7 (and support end 21) the cartridge 1 is depicted with ahousing seal member 25 thereon. In the example depicted, the housingseal member 25 comprises an o-ring 26 configured to form a radially(outwardly) directed, seal with a (surrounding) housing component,during installation.

Typically, a largest radial dimension of width, indicated generally orby dimension X, FIG. 1A, of the cartridge 1, at a selected locationwithin 50 mm of media end 3 and cartridge end 7, is a radial dimensionadjacent a largest radial reach of the seal member 25. Typically, thislocation is within 40 mm of media end 3 and cartridge end 7, usuallywithin 30 mm of media end 3, and cartridge end 7 and most preferablywithin 15 mm of cartridge end 7.

Referring to FIG. 1A, it is noted that for the example depicted, at end3 a portion of the media 2 extends axially beyond end 21 of the support20. This optional extension, which is usually no more than 10 mmtypically no more than 5 mm, sometimes no more than 3 mm, and which canbe 2 mm less, for example 1 mm or less, but usually at least 0.5 mm, isan optional extension that can provide advantage. In particular, itcreates a flexible media tail region that can assist in providing asecondary seal adjacent the end of a support on which the cartridge 1can be mounted during typical use and also potentially against anadjacent end of the housing. Thus, referring to FIG. 1A, typically atend 3, the media 2 has an end tip 3 t that is not directly radiallyengaged by any portion of support 20 and is not embedded with any endcap material or similar material, but rather is a “free end tip 3 t.”

Typically, the widest portion of the cartridge 1, in a radial direction,adjacent, but typically spaced from tip 3 t, by no more than 20 mm, atend 3, and at a location of the seal 26, has an overall width dimensionof no greater than 20 mm, typically no greater than 15 mm and often nogreater than 12 mm. This, again, is the dimension indicated in FIG. 1Aat X, and is meant to refer to a dimension without distortion of seal 25by sealing engagement with structure. It may be referred to as theundistorted cartridge radial width dimension adjacent the housing seal.This dimension X, FIG. 1A, is usually at least 5 mm less than the pleatdepth adjacent end 14, typically at least 10 mm less, sometimes at least15 mm less.

The inner pleats 10 are characterized herein as relatively sharp. Thisis because the pleat tips 10 t adjacent end 4 are typically quite sharpin definition, not widely rounded. The inner pleats 10 may be relativelywide themselves, for example, with sides 10 a, 10 b diverging at anangle of at least 30° typically at least 40° for example 40°-70° inextension from the inner pleat tips 10 t at a location adjacent end 4.

Referring to FIG. 1A, the support 20 includes a seal support ring, endring (seal end ring) or seal support member 27 adjacent end 21; the sealsupport member 27 defining a groove 27 g for receipt of seal such aso-ring 26, therein. It will typically be the portion of the end member27 that defines the groove 27 g that provides for the widest depthdimension X, FIG. 1A, in combination with the seal 26, adjacent end 7 ofthe cartridge.

Referring again to FIG. 1, the support 20 preferably not only providesfor seal support, at region 27, but also provides for radial support ofthe media 2. Thus, the support 20 includes a longitudinally extendingmedia support region 29 that extends between support ends 21, 22.

With respect to detail concerning the example media support 20 depicted,attention is directed to FIG. 5. Of course variations in structure canbe made, as will be understood from the following.

In FIG. 5, the example support 20 is depicted independently of the media2 and seal member 25. With respect to FIG. 5, it is noted that in atypical approach to assembly in cartridge 1, discussed below, thesupport 20 is not made independently of the cartridge 1. That is,typically, the support 20 is injected molded onto the media 2, for atypical approach to manufacture of cartridge 1. Such a support 20 willsometimes be characterized herein as “molded-in-place” or by similarterms. The view of FIG. 5, which shows features of the support 20independently of the media 2, allows for an understanding of certain,selected, preferred support 20 features. It is also noted that some ofthe techniques and advantages described herein can be obtained in anarrangement in which the support is not molded-in-place on the media 2,but rather is separately formed and then is attached to the media 2 toform a cartridge.

Referring to FIG. 5, the support 20 can be seen as including alongitudinal support section 29 comprising a plurality of longitudinalribs 30 in extension between ends 30 a, 30 b. The ribs 30 are spaced,radially, around a central axis X, FIG. 1. Typically, the ribs 30 extendfrom adjacent end 4 of the media to a location at least 50% of adistance toward the first end 3 of the media, usually at least 75%,typically at least 80% and often at least 90% of this distance.

Referring to FIG. 5, ends 30 a of the ribs 30 are generally positionedadjacent end or end region 21 of support 20. The opposite ends 30 b aregenerally positioned adjacent end 22. In the example depicted, the ribs30 are straight in extension between the ends 30 a, 30 b, becausepreferably they are configured to engage and extend along outer pleattips 11 t. When this is the case, the number of ribs 30 will typicallycorrespond to the number of outer pleats 11, although alternatives arepossible. Also, typically the ribs 30 will be radially evenly spacedaround central axis X, since typically the pleats 11 will also besimilarly spaced. Alternatives are possible. Engagement of the ribs 30with the pleats 11 and pleat tips 11 t (and with the ribs 30 extendinggenerally straight in extension between end 30 a, 30 b, with even radialspacing around axis X) will typically be preferred as it helps securethe media 2 and the pleats 11 in a preferred configuration, of the typedescribed. (Preferably there are no ribs 30 that are not positionedalong a pleat tip 11 t).

The cartridge 1, of FIG. 1, using support 20, is provided with a pleatshape or spacer arrangement not viewable in FIG. 1, but viewable in FIG.5 at 35. In general, the pleat spacer arrangement 35 is an arrangementthat comprises relatively rigid projections that extend radially towardaxis X and into spaces between the various ones of the outer pleats 11(FIG. 8), to help ensure proper pleat spacing/shape. This helps protectthe media 2 against pleat collapse, etc. For the particular exampledepicted, the pleat spacer arrangement 35 is provided as an outside orexterior spacer arrangement, with the projections extending between theouter pleats 11, at a location around an outer perimeter of the media 2.

The terms “exterior” or “outside” when used in the context ofcharacterizing spacer arrangement 35, is meant to indicate that thespacer arrangement is generally configured around an outside of themedia 2, with pleat spacing portions positioned between outwardlyextending pleats 11. The terms “exterior” and “outside”, then, refer tothe fact that the pleat spacer 35 is generally around an exterior of themedia 2, not an interior.

Referring to FIG. 5, and in general in reference to pleat spacerarrangement 35, the assembly includes at least one intermediate pleatspacer 36. The term “intermediate” in this context, is meant to refer toa pleat spacer 36 positioned axially spaced (i.e. in the direction ofaxis X) from each of ends 22 and 21 of support 20, and spaced from eachof ends 3, 4 (FIG. 8) of the media 2. The particular pleat spacerarrangement 35 depicted, includes three, spaced, intermediate pleatspacers 36, 37, 38. In more general terms, the pleat spacing arrangement35 will typically include at least one, and usually a plurality of,intermediate pleat spacers (36, 37, and 38). The typical number will beat least two and usually there will not be more than 5; the numbertypically being related to a length of the cartridge 1 and the nature ofsupport preferred for the media 2, for the intended use.

Referring to FIG. 5, intermediate pleat spacer 36 is configured tosurround an outer (or exterior) surface 20 of the media 2; and, to havea plurality of spaced radial projections 36 r that extend radially totips 36 t in a direction toward the central axis X and which extend,generally, between outer pleats 11, in the assembled cartridge 1,FIG. 1. Similarly, intermediate pleat spacer 37 comprises a plurality ofspacers 37 r directed, generally, radially inwardly to tips 37 t, i.e.,toward central axis X, and positioned between outer pleats 11. Finally,pleat spacer 38 comprises a plurality of radial extensions 38 r thatextend generally radially inwardly to tips 38 t towards the central axisX, and which are configured to be positioned between adjacent ones ofouter pleats 11.

It is noted that in the example cartridge 1 depicted, the amount ofextension (or radial dimension) toward axis X inwardly of tips 38 r isless than tips 37 t, which is less than tips 36 t. The reason for thisis that for the example cartridge 1 depicted, the pleat depth of themedia 2 decreases as it extends toward end 21 from 22 as discussed abovein connection with FIGS. 8-10.

Still referring to FIG. 5, typically ribs 30 and pleat spacers 36, 37,38, are molded integral with one another, for convenience. A particular,convenient, assembly approach is described further herein below.

The particular configuration of the pleat spacers 36, 37, 38 (i.e.,spacer arrangement 35 generally) is generally a matter of choice for theapplication of concern and the methods of concern. Typically, thepattern defined by the spacers (36, 37, 38) will correspond to thepattern intended for the media 2, with respect to the definition of theperimeter configuration. Whether or not each one of the spacers (36, 37,and 38) is in a plane perpendicular to central axis X is a matter ofchoice, in part depending on the particular approach to manufactureused. Whether or not the upper and lower surfaces of the spacers 36, 37,38 (upper and lower in this context referring to the extension of FIG.5) are planar, is also a matter of choice depending on the method ofmanufacture chosen. The particular configuration depicted in FIG. 5 isconvenient and effective, but alternatives are possible.

The spacing of the pleat spacers 36, 37, 38 from one another, and fromadjacent ones of ends 21, 22, is a matter of choice for accomplishingthe desired support for a given system. Typically, spacers 36, 37, 38will be spaced relatively evenly from adjacent ones of the spacers 36,37, 38 and relatively evenly from opposite ends 21, 22. Thus, forexample, each could be spaced from an adjacent spacer by about 20-30% ofthe distance between the ends 21, 22.

Still referring to FIG. 5, at end 22, which is an end of support 20 thatwill be positioned adjacent end 4 of the media 2, FIG. 1, the support 20(in cartridge 1) includes an end piece 40. End piece 40 will sometimesbe referred to as a media end piece or as a media support end piece orby similar terms. The end piece 40 is generally positioned to extendacross an end of the media 2 at end 4, i.e., an end remote from theoutlet end 7 of the cartridge.

In general, the end piece 40 interiorly closes ends of the pleats 10, 11adjacent media end 4. When, the support 20 is molded-in-place, it istypically formed with end 4 of the media 2 embedded in material fromwhich the end piece 4 is formed. When it is said that the end piece 40“interiorly closes” the ends of pleats 10, 11, it is meant that theclosure is at least on an inside of the media 2, i.e. at a downstreamside of the media.

The end piece 40 can be an “open” end piece or a “closed” end piece. Bythe term “closed” in this context, it is meant that the end piece 40would include no central aperture therethrough, in communication with anopen interior 2 i of the media 2 (interior 1 i of the cartridge 1),FIG. 1. For the particular cartridge 1 depicted, the preferred end piece40 is “open,” in that there is a central aperture 40 a therethrough,that communicates with the open interior 2 i of the media 2 (i.e., openinterior 1 i of the cartridge 1), FIG. 1. When the cartridge 1 isinstalled for use, a portion of the housing can optionally projectthrough aperture 40 a, stabilizing the cartridge 1. Also, when thecartridge 1 is installed for use, the optional aperture 40 a often besealed closed to avoid a leak path with respect to operation of thecartridge 1.

Referring to FIG. 5, the end piece 40 for the example embodimentdepicted, has an outer perimeter 40 p comprising a plurality ofalternating radially inwardly extending sections, gaps or recesses 40 iand outwardly projecting fingers, flanges or sections 40 o. The recesses40 i are typically positioned in axial overlap with end of flutes alongan exterior or upstream side of the media 2. While alternate perimeterdefinitions are possible, this definition of alternating outwardprojections 40 o and inwardly projecting recesses or sections 40 i isdesirable, because it allows for a longitudinal (axial) flow of gases(e.g., air) in a direction along the outer surface 2 o (FIG. 8) of themedia 2, between outer pleats 11, adjacent end 4 and between projections40 p. This provides for a convenient, less restrictive, gas flow.Alternative shapes for end piece 40 are possible, however.

Typically, the number of projections 40 o and recesses 40 i correspondsto the number of pleats 11.

Typically, each of the recesses 40 i projects radially inwardly towardcentral axis X, a distance of at least 10 mm (relative to theprojections 40 p) usually at least 15 mm and often an amount within therange of 20-40 mm. Also typically the recesses 40 r project towardcentral axis X, a distance of at least 25%, usually at least 30%, andoften an amount within the range of 40-60%, inclusive, of the distancebetween outermost parts of the projections 40 p and the central axis X.Typically, the projections 40 p are spaced apart (at outermost tips) byat least 30 mm, usually at least 35 mm; and, by an angular definitionaround central axis X of at least 30°, typically at least 40°.

The depth of the recesses 40 i characterized in the previous paragraphis not critical, but does provide for advantage. In particular, itensures a good, open, area along a longitudinal (axial) flow paththrough end piece 40 down in between outer pleats 11 during operation,which is a favorable flow path for managing restriction issues.

Referring to FIG. 5, end piece 40 generally includes a central region 45that extends across an otherwise open interior end of the media 2 at end4, FIG. 1. Referring to FIG. 1, central region 45 is defined by an innersurface 45 i and outer surface 45 o; the inner surface 45 i being thesurface that faces an interior 1 i the cartridge 1 (and media end 3,cartridge end 7 and support end 21); and, the exterior surface 45 obeing an opposite surface.

In FIG. 1B, an enlarged fragmentary view of a portion of the cartridge1, FIG. 1, is provided, for some convenient inspection on end piece 40.In general, the aperture 40 a, referenced above, extends through centralregion 45, in communication between inner surface 45 i and outer surface45 o.

Within the interior surface 45 i, end member 40 (i.e., central portion45 of cartridge 1 generally) includes a receiver recess 46 r. Thereceiver recess 46 r generally comprises a recess in a projection 46projecting in a direction (of extension of central axis X) away from end7 of the cartridge 1, FIG. 1. It is not, however, meant that theprojection 46 necessarily extends parallel to central axis X. Typically,the central recess 46 r is defined by a wall symmetrical in extensionaround central axis X, although alternatives are possible. The receiverrecess 46 r is defined by a wall or projection 46 having surface 46 pand is configured to optionally to receive, projecting therein,structure of certain preferred types of housings with which thecartridge 1 can be used, as discussed below.

It is noted that the optional aperture 40 a is provided in communicationwith recess 46 r, with central axis X passing therethrough. When theoptional aperture 40 a is used, this will be a typical position. Incertain applications, a portion of a housing that optionally projectsinto recess 46 r will also be configured to project completely throughaperture 40 a, in a preferred manner, discussed below.

Referring to the wall 46 p of surface 45 i that defines the recess 40 a,it is noted that for the example depicted, FIG. 11B, surface 46 p isgenerally frusto-conical or truncated; reducing in inner perimetercross-dimension definition (typically diameter) in extension in ageneral direction of axis X away from media end 3 and support end 21. Atypical configuration will have such a slant or frusto-conical shape toit, with the side wall 46 p extending, generally, radially inwardly atan angle of about 85°-99.5°, inclusive, relative to a planeperpendicular to central axis X, in extension away from media end 3 andsupport end 21. Alternatives are possible.

Referring to FIG. 1B, it is noted that the aperture 40 a in theparticular example depicted, has been fitted with (i.e. is lined with) aliner or grommet 48. The particular liner or grommet 48 depicted,includes an optional central aperture 48 a therethrough, correspondingin part to aperture 40 a. The grommet 48, when used, will typicallycomprise a resilient, seal-type, material.

Typically, the recess 46 r extends, axially, a distance of at least 15mm usually at least 20 mm, often 20-40 mm, inclusive, in extensionbetween an innermost end 46 i and on outermost end 46 o, FIG. 1B. Theliner or grommet 48 will typically extend, axially, at least 10% of anaxial extension (extension in the direction of axis X) of recess 46,typically an amount within the range of 20-40%, inclusive, of thisextension.

Referring to FIG. 1, for the particular cartridge 1 depicted, the outersurface 45 o of the end piece 40, includes an optional outer receivinggroove 50 therein. The outer receiving groove 50 is a groove that isopen in a direction away from media end 3 and extends generally towardend 7 from regions adjacent end 8. The groove 50 is typically andpreferably at least 5 mm deep in axial extension from immediatelyadjacent portions, typically surrounding portions, of end member 40,typically at least 8 mm deep and often 8-20 mm, inclusive, deep.Typically, the groove 50 is at least 5 mm wide, typically at least 6 mmwide and often 6-30 mm, inclusive, wide, in extension between radiallyinner surface 50 i and radially outer surface 50 o thereof. Usually itis not more than 20 mm wide. Typically the radial inner surface 50 i isdefined by a wall 52, which, along an interior surface thereof, definesrecess 46 r. Typically, the wall 52 extends axially in a direction awayfrom end 7 to a location further than an end 4 of the media, typicallyat least 5 mm further and often at least 10 mm further. In the exampledepicted, the wall 52 defines a tip 52 t, which also defines aperture 40a discussed above.

The optional receiving groove 50 is typically and preferably configuredto mate with portions of a main filter cartridge in an air cleanerassembly.

Attention is now directed to FIG. 5 and to optional projectionarrangement 55 on outer surface 40 x of end piece 40. Optionalprojection arrangement 55 is typically relatively narrow in maximumwidth (typically not more than 10 mm) and projects in a direction awayfrom surrounding portions of surface 45 x, a distance of at least 0.5mm, usually at least 1 mm, and typically not more than 10 mm. Theparticular optional projection arrangement 55 depicted is a continuousring 55 r, but alternatives, such as segmented rings, are possible. Theprojection arrangement 55 comprises an optional contact region forengagement with the main filter cartridge, in selected uses of thecartridge 1.

Attention is now directed to FIG. 7, a side elevational view of support20, with attention particularly directed at end 21. Around end 21,spaced gussets 57 are shown slanted outwardly to rim 27 r of groove 27g. The gussets 57 facilitate positioning an o-ring in groove 27 g. Inparticular, the o-ring can be pressed against the gussets 57, and then,with pressure toward end 22, the o-ring will spread and eventually snapover rim 25 r and into groove 27 g.

In FIG. 1, an example dimension is indicated as follows: AA=392.6 mm. Ofcourse, alternate dimensions can be used.

In FIG. 2, an end view of cartridge 1 is, shown, taken, generally,toward end piece 40. An example dimension is provided as follows:AB=135.3 mm diameter.

In FIG. 3, an end view taken toward end 3 is depicted. In the schematicdepiction, recess 46 can be viewed.

In FIG. 4, an exploded view of the cartridge 1 is depicted. The variouscomponents as previously described and viewable include: media 2,support 20, grommet 48 and o-ring 26.

In FIG. 7, a cross sectional view of frame member 20 is shown. Exampledimensions are indicated as follows: AC=389.2 mm; and, AD=133.1 mm.

From review of FIGS. 1 and 1A, again, it can be understood that in theexample arrangement depicted, the media at end 3 projects axially beyondend 21 of support 20. The amount of this extension, when present, willtypically be no more than 10 mm typically no more than 5 mm and often atleast 0.5 mm, sometimes at least 1 mm. The portion of media end 3 thatextends beyond any structural support of support 20, i.e., beyond end 21of support 20, will sometimes be referred to as a “seal end” or “endtail” and by the designator 3 t, FIG. 1A. This seal end or tail 3 t canprovide a number of advantages. First, being flexible, it can push downinto and against structure of the housing adjacent (both axially andradially) end 3 of the media. It, thus, can help provide secondarysupport to sealing, in addition to the primary cartridge seal 26.Further, this seal end or tail 3 t can provide a wiping effect as thecartridge 1 is installed/removed.

Possible variation in the cartridge 1 can be understood by considerationof FIGS. 1C, 1D, 1E and 2A. In FIG. 1E, the cartridge analogous tocartridge 1 is depicted, except having no optional projection 55 (FIG.1B) thereon; and, having a variation in a grommet 48 v, from grommet 48.In FIG. 1C, like reference numerals are used to FIG. 1, generally,except for designation of the grommet, which in FIG. 1C is indicated at48 v. In FIG. 1C, example dimensions are indicated as follows: ZQ=12.2mm; ZS=138.7 mm; ZR=392.6 mm.

In FIG. 1D, an enlarged fragmentary view of an identified portion ofFIG. 1C is provided. This is the region adjacent seal 26, discussedabove in connection with FIG. 1A. In FIG. 1D, example dimensions areindicated as follows: YH=5.5 mm; YI=7.5 mm; YJ=9.1 mm. In FIG. 1E, anenlarged fragmentary view of an identified portion of FIG. 1C isprovided. From inspection of FIG. 1E, it can be again seen that thecartridge 1 depicted does not have the optional projection 55 r, FIG.1B. It can also be seen that the alternative grommet 48 v includes outerrings 48 r, embedded in structure from which support 20 is formed, as aresult of manufacture in accord with an approach discussed below. Theoptional rings 48 r are not shown in the grommet 48, FIG. 1, but can beused with that embodiment. In other manners, the features of FIG. 1E aregenerally analogous to those discussed and described in connection withFIG. 1B. In FIG. 1E, example dimensions are indicated as follows:ZV=24.6 mm; ZT=47 mm; and, ZU=18.4 mm.

In FIG. 2A, an end view analogous to FIG. 2, but of the cartridge ofFIG. 1C without the optional projection 55 r is depicted. Other featuresare generally analogous to those discussed above in connection with FIG.1, and shown in FIGS. 1C and 1D. In FIG. 2A, example dimensions providedare indicated as follows: ZL=10 mm radius; ZM=45°; ZN=1 mm radius;ZO=61.5 mm; and, ZP=123 mm.

II. Example Manufacture of the Filter Cartridge of FIGS. 1-10

A variety of techniques can be used to construct a cartridge havingfeatures in accord with the present disclosure. The preferred cartridge1 configured as depicted in connection with FIGS. 1-10, and using acartridge support 20 as described to support media as configured inFIGS. 8-10, will typically be made by preforming media into the shapeshown described in connection with FIG. 8 and then (injection) moldingthe support 20 in place, onto the media. This can be done with the moldconfiguration that supports the media 2 in the desired configuration,while directing the polymeric material appropriately.

Typically and preferably, with techniques described herein, and in whichthe support 20 is molded-in-place, preferably the injected material forforming the molded-in-place support 20 is provided exteriorly of themedia 2. That is, preferably at locations extending along the length ofthe media 2, except immediately adjacent end 4, the resin material isnot injected in the interior 2 i of the media 2, but only along theexterior 2 o. The resin will penetrate into the media somewhat, butpreferably along most of the lengths of the pleats 11 it does not extendradially completely through the media 2 enough to project radiallyinwardly from the media 2 except, in some instances, in the regionimmediately adjacent end 4, and then, as limited as reasonable whileobtaining good adherence/seal.

Typically and preferably, a single shot mold approach is used, toaccomplish construction of the entire support 20 in one injection stepin the molding. The support configuration depicted in FIG. 5, withsupport features as described, is configured to allow for this.

As discussed herein above, the support 20 can be provided with a grommet48 (or 48 v) positioned at an end thereof. Typically, when the support20 is molded-in-place, for example using an injection molding operationas described, the grommet 48 (or 48 v) is prepositioned in the mold, sothat as the molding occurs, the grommet 48 (48 v) becomes secured inplace.

The material used for the support 20 will typically be a material havingsufficient strength to provide the desired support to the media 2, inuse. An example would be a thermoplastic, such as a polypropylene orpolyethylene. Alternatives are possible.

For the grommet 48 (or 48 v), typically, a thermoplastic elastomer (tpe)will be used. A typical grommet will comprise a resilient materialcapable of forming a seal and may, for example, be formed from a resinto have a hardness of at least 30 Shore A, typically at least 40 ShoreA, for example 50-80 Shore A. Alternatives, of course, are possible.

The material chosen for the media is a matter of choice, for the flowcharacteristics and filtering characteristics and filteringcharacteristics desired. Filter media of a type typically used in safetycartridges can be used.

The media will include a longitudinal seam therein. The seam can beformed with sonic welding, heat welding, or adhesive, or it can beconfigured to be sealed by the resin forming the frame structure, ifdesired.

III. An Example Filter Assembly Using Cartridge 1 as a Safety Filter

A. An Example Filter Assembly and General Features, FIGS. 11-13B

In FIGS. 11-13B, a filter assembly (for example an air cleaner) havingadvantageous features and using a secondary or safety cartridge inaccord with cartridge 1, discussed above, is depicted. Many of thefeatures are variations of those described in one or both of WO2009/014986 and WO 2012/116314, referenced above and incorporated hereinby reference. Advantageous variations, however, are provided asdiscussed.

Attention is first directed to FIG. 13. In FIG. 13, a gas filterassembly 100 configured as an air cleaner assembly, is depicted incross-sectional view. The filter assembly 100 comprises a housing 101having, operably positioned therein, a main or primary filter cartridge102 and a secondary or safety cartridge 1 in accord with the presentdisclosure.

In general, air to be filtered flows into housing 101 through gas (air)flow inlet arrangement 105. The air is directed through primary or maincartridge 102, with “out-to-in” flow and then through a secondary filter1, with a “out-to-in” flow. The filtered gas (air) exits housing 100through outlet flow arrangement 106.

Attention is now directed to FIG. 11, in which the housing 101 isdepicted without the primary filter cartridge 102 and secondary orsafety cartridge 1 installed. Referring to FIG. 11, the housing 101comprises a housing body or base section 109 and an access cover 110.The housing body or base section 109, in the example depicted, definesan open end 109 a and an opposite end 109 b. The open end 109 a is anaccess end, over which the access cover 110 is removably positioned. Theaccess cover 110 is shown removably secured in place by latcharrangement 111.

In the example assembly depicted, the inlet 105 and outlet 106 arepositioned on the body section 109, although alternatives are possible.Positioned on the access cover 110, is an optional evacuator outlet 114,closed by an evacuator valve arrangement 115. Some dust and water can beejected from housing 101 through evacuator outlet 114 and valve 115, inuse. Such evacuator arrangements are sometimes referred to as“precleaners” and are used in a wide variety of air cleaner systems.When an air cleaner assembly uses such an optional precleaner, it issometimes referred to as a “two-stage” air cleaner, the first stagebeing the precleaner and the second stage being represented by thefilter cartridge arrangement.

Still referring to FIG. 11, as gas flow (i.e. air flow) enters throughinlet or inlet tube arrangement 105, it is directed into optionalcyclonic ramp arrangement 117, by which it is directed into a helical orcyclonic flow around central axis X. This helps direct some of the waterand/or particulate material contained within the air flow, intoevacuator arrangement 114, before that material impinges on the primaryfilter cartridge 102, FIG. 13. To facilitate such a cyclonic movement ofthe air, preferably inlet arrangement 105 is configured with an air flowinlet direction represented by an axis A that is tangentially directedrelative to sidewall 109 s.

To facilitate precleaning, the housing 101 includes a shield section 118projecting toward access cover 110 from end 109 b, and an optionalsecond shield section 119 projecting toward and 109 b and outlet 106,from access cover 110. These optional (but preferable) shield sections118, 119 will be positioned around opposite ends (respectively) of themain filter cartridge 102, FIG. 13, to help isolate flow of water and aportion of particulate material from inlet 105 to ejector or evacuatoroutlet 114, to advantage.

Still referring to FIG. 11, access cover 110 includes an end wall or end110 e, having an optional central projection 120 thereon, that projects,generally, toward end 109 b and outlet 106. In the example depicted, theprojection 120 is positioned with central axis X extending therethrough,which will be typical.

The central projection 120 can have a variety of specific configurationsand shapes. It can be configured as a ring, be solid or hollow, or itcan have a cross-sectional definition defined by fins or otherstructures.

With respect to selected features of projection 120, attention isdirected to FIG. 11A. Attention is particularly directed to end 120 e,of access cover or central projection 120; end 120 e being an end remotefrom end wall 110 e. Optional but preferable features at end 120 e ofinterest include the following. First, the access cover 110 includesthereon, a projection 123 which, in the example depicted, comprises aring projecting in the general direction of axis X away from end 110 eand toward end 109 b. The projection 123 is sized and configured toengage width cartridge features as discussed below.

The ring 123 surrounds an optional central recess or receiver 124 inprojection 120. The recess 124 is preferably configured to receive,projecting therein, selected portions of the housing 101 and cartridgearrangements as discussed below. Typically, the recess 124 projects atleast 10 mm usually at least 15 mm and often an amount within the rangeof 20-40 mm, inclusive, toward end 110 e from tip 123 t of projection123.

Still referring to FIG. 11A, it is noted that ring 123 is typically atleast 5 mm long in extension from a surrounding portion 125, ofprojection 120 to tip 123, usually at least 10 mm long and often has alength within the range of 10-25 mm.

Referring back to FIG. 11, the housing 101 includes a central cartridgesupport 130 therein. The central cartridge support 130 is positioned inextension from adjacent wall 109 b toward access cover 110. The centralcartridge support 130 generally includes a base end 131, a poroussidewall 132 and a cartridge support end 133. The base end 131 ispositioned adjacent end 109 b, and includes a gas flow aperture 131 atherethrough providing gas flow communication with outlet 106. Thecartridge support end 133 is remote from wall 109 b, and is directedtoward access cover 110.

The central cartridge support 130 can be formed integral with aremainder of housing section 109. For the example depicted, however, thecentral cartridge support 130 comprises a separately formed piece whichis snap-fit in place by a snap fit arrangement 131 x, FIG. 11B, inengagement with a surrounding portion 135 of housing section 109. Thesurrounding portion 135 includes a flange 135 f, which surrounds aportion of central cartridge support 130.

It is noted that in some instances, the central cartridge support 130can be constructed to be removable from the housing section 109 onceinstalled. However, typically and preferably the cartridge support 130is non-removable from housing section 109, either by having been formedintegrally therewith (for example by being molded integral with otherportions of the section 109) or by having been installed with a snap-fitconnection not readily disconnected once established. Preferably thesupport 130 does not include any media, independent of a serviceablecartridge 1, 102.

Typically, the central cartridge support 130 is independent andseparable from any filter cartridge positioned within the assembly 100during use. That is, typically the central cartridge support 130comprises a portion of the housing 101, and remains with the housing 101during servicing of the cartridges 1, 102.

Referring to FIG. 11B, it is noted that flange 135 f projects towardaccess cover 110, to tip 135 t. The flange 135 f defines a sealingflange for the system 100 depicted. In particular, the outer surface 135o of flange 135 will form a seal surface for the main filter cartridge102; and, an inner surface 135 i of flange 135 will form a seal surface4 for the safety cartridge 1. Although alternatives are possible, thisis particularly convenient for installation of the cartridges 102, 1.

The support 130 is provided with an open interior 130 i surrounding axisX and positioned in air flow communication with outlet 106. Thus, aftergases after have been filtered by the main filter 102 and safety 1, theywill pass into interior 130 i and outwardly from housing 109 throughoutlet tube 106. It is preferred that the outlet 106 (and end 131 a insupport 130) have as large a cross-sectional area as reasonablypossible, so as to avoid undesirable additional restriction to air flowthrough housing 101. Selected features of the present disclosurefacilitate this, as discussed below.

At outlet 106 optional pressure tap 106 t, FIG. 11B, is provided,facilitating connection of a restriction indicator or pressure monitorin a typical conventional manner.

In FIG. 11A, support end 133 of central cartridge support 130 can beseen in detail. The support end 133 is the end of support 130 remotefrom base 131 and sidewall 109 b, and comprises an optional outer ringor shoulder 138 and a central projection 139. In the example depicted,the central projection 139 is positioned on central axis X. While thisis typical, alternatives are possible.

Positioned between shoulder 138 and central projection 139 at a locationsurrounding the central projection 139, the cartridge support end 133 ofcentral cartridge support 130 includes a receiving groove, recess orreceiver space 140. Receiver space 140 is, typically, at least 5 mmdeep, typically at least 8 mm deep, for example 8-25 mm deep, inclusive,in extension along the direction of axis X toward outlet 106 from asurrounding portion of the end 133, typically shoulder 138. The recess140 is typically at least 5 mm wide, for example 8-20 mm wide, and notusually more than 25 mm wide, in extension thereacross, between sidewall140 w and projection 139. Typically, the outerwall 140 w of recess 140is positioned spaced radially at least 10 mm radially inwardly from anouter portion of perimeter of support 130.

Still referring to FIG. 11A, it is noted that projection 120, and inparticular projection end 123 is typically, and optionally, sufficientlylong to at least start to extend into recess 140, when access cover 110is positioned on housing base 109.

Still referring to FIG. 11A, attention is now directed to centralprojection 139.

The central projection 139 includes, as it extends toward access cover110, a shaft or base 144 extending to a remote end or tip 145. Betweenbase 144 and tip 145, the projection 139 includes an optional butpreferable neck section 146. The optional neck section 146 is a narrowedsection in projection 139. Thus the projection 139, typically andpreferably has a tip 145 of large cross-sectional dimension (typicallydiameter) than another portion, i.e. the neck section 146, that ispositioned between the tip 145 and a base 144. This optionalconfiguration can provide for advantage, as discussed further below.

Referring to FIG. 11B, attention is directed to recess 150 r betweencentral cartridge support 130 and flange 135 f. The recess 150 r is arecess into which an end of a safety filter cartridge 1, discussedbelow, extends during installation. It is, in particular, a recess intowhich an end 7 comprising media end 3, FIG. 1, projects. It is notedthat the recess 150 r is relatively narrow in radial dimension,typically its widest dimension being no greater than 30 mm, preferablynot greater than 25 mm, usually not greater than 20 mm, sometimes 15 mmor less. A reason for this is that it is preferable that radialdimension in the region of section 131 of central cartridge support 130,of the cartridge 1 take up as little radial dimension as reasonable soas to facilitate flow through filter assembly 100 with without undueaddition to restriction. This is discussed below.

The recess 150 r will sometimes be referred to herein as a safetycartridge end receiving recess 150 r, or by similar terms. In a typicalembodiment, it will be formed between the flange 135 f and a region ofcentral cartridge support 130 adjacent end section 131.

Attention is now directed to FIG. 12, in which the housing 101 isdepicted with the safety cartridge 1 fully installed, but without theprimary filter cartridge 102 positioned. It can be seen that the safetycartridge 1 is installed by being pushed over the central cartridgesupport 130. Selected portions of the interaction among the cartridge 1,central cartridge support 130 and housing 101 are discussed inconnection with FIGS. 12A and 12B, each of which is an enlargedfragmentary view of a portion of FIG. 12.

Referring first to FIG. 12A, an interaction between end 7 (and media end3) of safety cartridge 1 and recess 150 r can be seen. First, it can beseen that as a result of not being pleated (i.e., being of very limitedor no pleat depth) near end 3, the cartridge 1 will fit in therelatively narrow recess 150 r, with seal 26 engaging inner wall 135 iof flange 135 f, to form a radially (in the example outwardly) directed,housing seal that is releasable. Further, it can be seen that free endor tip 3 t of the media 2, i.e. a portion of media 2 not embedded in anend cap and not surrounded by media support 29 can be pushed to, or nearto, an end of recess 150 r, and will tend to pick up and pull (wipe) outof the recess 150 r particulate material that may migrate into thisregion during use and/or servicing.

It can also be seen by referring to FIG. 12A, that due to the verynarrow construction of the cartridge 1 in radial dimension at seal 26, anarrow recess 150 r can be used to advantage, to avoid undesirableaddition to restriction from the size of outlet 106, and outlet end 131a of central cartridge support 130, while (at the same time) allowingmaximal radial width within housing 109 for the main filter cartridge102, as discussed below.

Indeed, typically the maximum radial width of recess 150 r for insertionof end 7 of cartridge 1 therein, is at least 5 mm smaller, usually atleast 10 mm smaller, and sometimes at least 15 mm smaller than a maximumpleat depth of the media 2, of cartridge 1, adjacent end 4, FIG. 1.

Attention is now directed to FIG. 12B, an enlarged fragmentary viewdepicting an interaction between the cartridge 1 and the centralcartridge support 130 at support end 133. In particular, cartridge 1 canbe seen positioned with central recess 46 r receiving, projectingtherein, central projection 139 on central cartridge support 130. Forthe particular example depicted, the central projection 139 projectscompletely through recess 46 r (and aperture 40 a) and optional grommet48 v, with tip 145 projecting through aperture 40 a. The optionalgrommet 48 v is shown engaging the central projection 139 therearound,in the particular example by engagement at least with neck region orsection 146. In the example depicted, the optional grommet 48 v is shownsecured within end projection 46 by having been positioned in a mold andhaving section 46 molded thereto, with physical connection provided bygrommet rings 48 r, FIG. 1E.

Also, referring to FIG. 12B, it can be seen that projection 45 p on endpiece 20 projects into receiver 140 on the central cartridge support130. Further, it can be seen that projection 123 on the access cover 110projects into recess 50 on secondary or safety cartridge 1.

In the example depicted in FIGS. 12A and 12B, it is noted that thecartridge 1 does not include the optional projection 55 r, FIG. 1B,thereon. Of course, such a projection can be used to advantage, ifdesired. Advantages for such an optional projection 55 are discussedbelow.

In FIG. 12C, a view generally analogous to FIG. 12 is depicted. In FIG.12, some examples dimensions are indicated as follows: YC=354.6 mm;YD=115.8 mm; YE=65.6 mm; YG=539.7 mm; YF=423.3 mm.

Attention is now directed to FIGS. 13, 13A and 13B. Here, filterassembly 100 is depicted with both the primary filter cartridge 102 andsecondary filter cartridge 1 in place. Referring first to FIG. 13, theprimary filter cartridge 102 can be seen as having opposite ends 102 a,102 b, with media 150 extending between opposite first and second mediaends, 151, 152, corresponding to cartridge ends 102 a, 102 brespectively. The media 150 will typically be pleated, althoughalternatives are possible. In the example depicted, the media 150 has agenerally conical or frusto-conical outer perimeter 150 p defined byouter pleat tips with outer perimeter 150 p decreasing incross-sectional size in extension from end 151 to end 152. Typically,the extension is at a conical angle, i.e. an inward taper, of at least0.5°, typically not more than 5°, and often within the range of 1°-5°.

Referring to FIG. 13B, the cartridge 102, includes, positioned on themedia 150 at end 151, and end cap or end piece 154. The particular endpiece 154 depicted, is molded-in-place, although alternatives arepossible. Typically, the end piece 154 when configured as shown, wouldbe molded from a material such as foamed polyurethane, that can alsooperate as a seal material as discussed below. Typically, the materialwill be molded to an as “molded” density of no greater than 0.32 g/cc,typically no greater than 0.24 g/cc, for example 0.16 g/cc-0.24 g/cc,and, will have a hardness, Shore A, of no greater than 20, typically nogreater than 18, and often within the range of 10-18, inclusive.

Referring still to FIG. 13B, end cap 154, which is at main cartridge end102 a, is shown with a central aperture 155 therethrough, which willserve as an “flow aperture” for main cartridge 102, in the example a gasflow exit aperture. In the example, the aperture 155 is defined by, andis surrounded by, housing seal region 156, which, in the exampledepicted, is a portion integral with a remainder of end cap 154. Sealregion 156, in the example depicted, is positioned and configured toform an inwardly directed radial seal around central axis X, andreleaseably in engagement with outer surface 135 o of flange 135 f.

Referring to FIG. 13, it is noted that an end 151 of media 150 is partof an end section of media that will project at least 10% usually atleast 20% and typically not more than 50% from media end 151 towardmedia end 150 b, while being surrounded by flange 118. This helpsprovide for desirable operation of the precleaner function in housing101. The flange 118 is preferably sufficiently large to still allow airflow to a region surrounding end section 151, for good filteringoperation. The tapering of media 150 facilitates this.

Still referring to FIG. 13, it is also noted that flange 119 surroundsend section 152 of the media 150 adjacent end 150 b. Typically, itsurrounds the media 150 over a length of extension at least 5%,typically not more than 20% from end 152 toward end 151. Support 119provides a centering function for the cartridge 102, and can providesome protection for the cartridge 1. Additional protection for thecartridge 102 is provided by end margin or wrap 148, which surrounds themedia 150 adjacent end 152.

Still referring to FIG. 13, it is noted that the media 150 includes aninner perimeter 150 i, typically defined by inner pleat tips, whichtapers downwardly in extension from end 151 to end 150 b. Typically, anangle of extension of inner perimeter 150 i relative to axis X is thesame as the angle discussed above for perimeter 150 p. It is furthernoted that, for the example depicted, the cartridge 102 includes aporous inner liner arrangement 160 around which the media 150 ispositioned. This is typical, but optional.

Referring to FIG. 13B, attention is directed to recess 162 in end piece154. The recess 162 can be an artifact, from a mold stand-off for themedia 150, during manufacture of end piece 154. It also can be used as areceiver recess for an optional projection member (not shown) within thehousing end 109 b. Both functions can be provided by the recess 162, or,in some, systems two different recesses can be provided.

Referring still to FIG. 13B, projection arrangement 163 (on end piece154) is shown engaging end wall 109 b of the housing section 109. Theprojection 163 can, for example, be a continuous ring, segmented ring,or a plurality of bumpers, to provide for cushion engagement with endwall 109 b to advantage.

Referring again to FIG. 13, attention is directed toward end 152 ofmedia 150. At end 152, the cartridge 102 includes a second end cap orend piece 170. End piece 170 generally comprises: an outer ring section171, which is in axial overlap with end 152 of the media 150; and,central section 172, which projects inwardly into an open filterinterior 102 i of cartridge 102, from end 152 of the media 150 towardend 150 a. Typically, end piece or end cap 170 is closed, i.e. it has nocentral aperture therethrough, although in some applications,alternatives are possible. Typically, section 171 is molded-in-place,for example, from a material similar to, or in some instances harderthan, that used for end piece 154; with central section 172 preformed,for example from a rigid plastic and then secured in place during themolding of section 171. Alternatives are possible. The seal section 171can, optionally, include a projection 163 x, analogous to projection 163but positioned to engage access cover 110.

Attention is directed to FIG. 13A, with respect to selected features ofprojection 172. Projection 172 generally includes an outer sidewall 173and an end section 174. The end section 174 is defined by: an innersurface 174 i that faces toward the opposite end piece 154 from endpiece 170; and, an opposite, outer, surface 174 o. In the outer surface174 o, end 174 forms a receiving groove 177 that surrounds a centralprojection 178. The receiving groove 177 is typically at least 6 mmdeep, usually at least 8 mm deep in deepest extension, from nearestsurrounding portions 177 x of end 174. The projection 178 generallyextends at least 10 mm, typically at least 15 mm and often an amountwithin the range of 15-35 mm, inclusive, from an immediately surroundingportion of groove 177.

Typically, the projection 178 on the central section 172 comprises acentral projection directed away from the first end piece and whichterminates at an end remote from the media first end at a location thatis spaced from the media second end at least 15% of a distance from themedia second end to the media first end.

The groove 177 is typically at least 4 mm wide and usually not more than25 mm wide, between inner and outer sidewalls 177 i, 177 o.

Along the inner surface 174 i, the projection 178 defines a receiverrecess 178 r into which the central projection 139 (of the centralcartridge support 130) and the central projection 46 of the secondarycartridge 1 project.

Also, along the inner surface 174 i, end 174 defines a projecting ring180 that projects into receiving groove 50 of safety cartridge 1 andreceiving groove 140 of central cartridge support 130.

Also referring to FIG. 13A, it is noted that the access cover projection123 projects into receiving groove 177 of the primary cartridge 102.

In the next sections, some advantages from the various featurescharacterized herein above will be discussed. Before turning to those,it is noted that there are some example dimensions provided in FIGS. 13and 13A. As with other example dimensions herein, these are meant to beexample of dimensions are workable in a system, but alternatives arepossible.

The example dimensions are as follows: ZA=605.2 mm; ZB=179.5 mm;ZC=354.6 mm; ZD=27.2 mm; ZE=47 mm; ZF=23.6 mm; ZG=20.8 mm; ZH=2 mm;ZI=33.2 mm; ZJ=37.7 mm; and, ZK=44.42 mm.

B. Advantages Relating from Preferred Features Characterized HereinAbove

1. Advantageous Safety Filter Cartridge Characteristics for Use with aTapering Main Filter Cartridge

Referring to FIG. 13, as indicated above, in a typical, preferred,application of features as characterized herein, the main filtercartridge 102 tapers in both outer perimeter 150 p and inner perimeter150 i definition, in extension from media end 151 to media end 152. Thismeans that the internal cross-dimension surrounded by media innerperimeter 150 i tapers downwardly along the same extension.

This can restrict the space available for safety 1, within interior 102i. As a result, in a typical application, the safety cartridge 1 isconfigured to project no further than a location of at least 90% of adistance between end 150 a and end 150 b of surrounding media 150,typically no greater than 85% of this distance and usually an amountwithin a range of 65-85% of this distance, in the direction of extensionfrom end 150 a toward end 1. This allows the tapering of inner perimeter102 i, to extend a definition quite narrow at end 150 b. Indeed, themedia 150, of the main cartridge 102, may in some instances, only clearend 8 of cartridge 1, by a radial dimension of 8 mm or less.

However, this means the safety cartridge 1 is of somewhat limitedlength, with respect to safety media 2. To avoid undesirablerestriction, the safety cartridge 1 is provided with pleated mediaadjacent end 4, to increase surface area available, and decrease facevelocity. This is an advantageous improvement, with a safety cartridgeused with a main cartridge that tapers downwardly, especially if themain cartridge tapers downwardly to a width too narrow to accommodate,conveniently, a substantially longer safety cartridge.

It can also now be understood how the relatively wide outer pleats 11 ofthe safety cartridge 1 adjacent end 4, can provide for advantageousflow. This is because the outer pleats 11 define spaces therebetween,along which the air can flow after it passes through the main filtercartridge 102 and as it is directed into the safety 1, to be directed tothe outlet 106. This too is advantageous for controlling restrictionincrease from the presence of the safety cartridge 1.

Referring to FIG. 13, to accommodate the relatively short safetycartridge 1, the main cartridge 102 includes a central projection 172that projects (a maximum amount in extension in a direction from end 152of the media toward end 151) at least 70 mm, typically at least 80 mmand often an amount within the range of 100-140 mm; and typically anamount of a distance between the ends 152,151 of at least 15%, typicallyat least 20% and sometimes an amount within the range of 24%-40% of thisdistance of extension.

2. Advantages from the Configuration of the Media Adjacent Media End 3

Advantages are also provided by the lack of pleats (or minimal pleatdepth) adjacent end 3 of the media 2 and safety 1 as discussed above.The advantages from this are that adjacent end 3, the media 2 andcartridge 1 take up relatively little radial dimension. Thus, theoverall cartridge 1 has relatively little radial dimension adjacent seal26 so it can fit into a narrow recess 150 r, FIG. 12A. This means theradial projection of the cartridge 1 around the air flow exit, does notcontribute, to an undesirable extent, to restriction to air flow to theoutlet 106, to advantage.

3. Advantages at the Interaction Between the Safety Cartridge 1 andCentral Cartridge Support 130

The central cartridge support 130 provides support to the safetycartridge 1 ensuring proper orientation within the assembly 100. Aengagement of particular advantage between the safety cartridge 1 andthe central cartridge support 130 occurs in the region of centralprojection 139.

First, to advantage, an optional cushion engagement is provided betweenthe central projection 139 and the safety cartridge 1, by grommet 48 (48v) when grommet 48 (48 v) is resilient. This helps avoid a hard plasticto hard plastic engagement at this location. The cushioning effect isprovided by constructing grommet 48 (48 v) from an appropriatelycushioned or flexible, i.e. resilient, material as discussed previously.

Also, in the particular example depicted, the central projection 139extends completely through aperture 40 a in the safety cartridge 1. Whenthis is the case, it is desired to provide a seal closing aperture 40 a.The optional grommet 48 (48 v) also provides for this by comprising aresilient material that releaseably, sealingly, engages projection 139.

In the example depicted, the central projection 139 includes an optionalhead or tip 145, i.e. wider portion, and a narrow neck section orportion 146. This also is advantageous in combination with the optionalgrommet 48 (48 v). In particular, as the safety cartridge 1 is pushedover central cartridge support 120, eventually head or tip 145 willengage grommet 48 (48 v). It will push through, expanding the aperturein the grommet 48 (48 v). Eventually it will project outwardly from thegrommet 48 (48 v) providing an interference fit as shown in FIG. 12B, bythe tip 145, being wider than the aperture in the grommet 48 (48 v),when the grommet 48 (48 v) surrounds the neck section 146. Thisinterference fit will help keep the cartridge 1 in place on the centralcartridge support 130 as the main cartridge 102 is installed andremoved, and as servicing occurs when the cartridge 102 is removed. Theamount of interference is preferably not so much that it can't beovercome by a service provider pulling on the safety 1, but is alsopreferably adequate to help secure the safety in position againstundesired movement, and thus provides advantageous effect.

4. Advantages from Projection/Receiver Interaction Among the SafetyCartridge 1, the Central Cartridge Support 130, the Main Cartridge 102and the Access Cover 110

In the system 101 depicted, as discussed, the central cartridge support130 and the safety cartridge 1 are relatively short, by comparison tothe length of extension of the main cartridge 102, and for that matter,the housing 101 in extension along the central axis X (i.e. in an axialdirection). The interaction described among the safety cartridge 1 atend piece 20; the central cartridge support 130 and cartridge supportend 132; the main cartridge 102 at end piece 170 and in particularsection 172 at end 174; and, the access cover 110, especially inconnection with projection 123 and recess 124, provide for a number ofadvantages. For example, the main cartridge 102 and the safety cartridge1 are well stabilized in their respective positions. Also, they aresecured in a desired orientation for proper operation and easyinstallation and removal. Further, the interaction helps ensure that themain cartridge 102 and the safety 1, are proper ones for the system 101of interest, and cannot be improperly installed; i.e. installed withoutappropriate and proper sealing.

5. Advantages from the Optional Projection Arrangement 55 r, FIG. 1B

The optional projection 55 r, FIG. 1B, can also provide advantage. Inparticular, it can form a bumper against which a portion of maincartridge 102, can press if the safety 1 is not fully installed beforethe main cartridge 102 is installed. This will help push the safety 1into a proper sealing position over central cartridge support 130. Insome instances, it may be desirable to form projection 155 r from arelatively resilient material, so as to facilitate this type ofengagement. This can be done with a molding operation that provides aresilient material at region 155 r if desired.

6. Advantages from a Free End of the Media at Tip 3 t

As explained above, preferably the media 2 is provided with a tip 3 tthat is free, i.e. is not embedded in an end cap, and is not surroundedby any portion of cartridge support 29. This is advantageous, in that itprovides not only for a narrow width dimension of the cartridge 1 atthis region, for insertion in the recess 150 r, but it also leaves thetip 3 t free to provide for a secondary sealing effect within recess 150r and also some cleaning effect as it is removed during servicing of thecartridge 1.

IV. Some Selected Variations, FIGS. 14 and 15

In FIG. 14, a schematic cross-sectional view of a housing analogous tothe view of FIG. 11 is depicted. The depiction of FIG. 14 is meant toindicate an example of a usable variation. Like features would have alike operation.

Referring to FIG. 14, the housing 300 depicted includes a main housingpart 301 having an access cover 303 thereon. The main housing part 301may be generally analogous to part 109, FIG. 11. The access cover 302may be generally analogous to access cover 110, FIG. 11. The particularaccess cover 302 is varied somewhat in the region of projection 305 inthat central recess receiver 306 is deeper than receiver 124, FIG. 11A.Also, it is surrounded by a second projection 307. However, it can beused in general in a manner analogous to access cover 109, FIG. 11.

In FIG. 15, a cross-sectional view of an alternate cartridge 350 to maincartridge 102 is depicted. Like features have like operation. It isnoted that a closed end 351, a projection 352 is shown comprising aportion of a liner 353 that extends completely between opposite end caps354, 355. The projection 352 can operate similarly to projection 172,FIGS. 13 and 13A. It is also noted that projection 352 includes an endhaving a recess 360 analogous to recess 178 r, and outer surface 361with a projection 362 thereon surrounded by a recess 363. These featurescan operate analogously to analogously described and depicted featuresfor the embodiment of FIG. 13A. Also, spaced centering fins 370 areviewable on outer surface 352 o. They are directed toward central axis Xand projection 362. The centering fins 370 will fit around ring 307,FIG. 14. The fins 370 preferably surround a portion of projection 362.There are preferably 3-8 such fins 370.

In FIG. 15, example dimensions are indicated as follows: Q1=520 mm;Q2=392.5 mm; Q3=14.5 mm; Q4=239.3 mm; Q5=98.5 mm; Q6=4 mm; Q7=3 mm;Q8=269.6 mm; Q9=160 mm; and, Q10=135 mm. Of course, the arrangement canbe implemented with alternate dimensions.

V. General Comments and Observations

In this summary, some selected, final summary characterizations of theteachings herein are provided. Among what is taught are:

1. A filter cartridge comprising: (a) an extension of media surroundinga central axis and defining an open interior; (i) the media having firstand second ends; and, (ii) the media being pleated adjacent the secondend and defining a plurality of inner pleat tips extending at an acuteangle, relative to a plane perpendicular to the central axis, of nogreater than 89°, in extension toward the first end; and, (iii) themedia being non-pleated at the first end.

2. A filter cartridge comprising: (a) an extension of media surroundingan open interior and having a first end and a second end; (i) at thefirst end, the media having no pleat greater than 3 mm in depth; and,(ii) at the second end, the media comprising a plurality of pleats eachhaving a pleat depth of at least 10 mm.

3. A filter cartridge according to any one of characterizations 1 and 2including: (a) a housing radial seal member positioned at a locationwithin 50 mm of the first end.

4. A filter cartridge comprising: (a) an extension of media surroundingan open interior and having a first end and a second end; (i) the mediacomprising a plurality of pleats each having a pleat depth decreasing inextension from the second end in a direction toward the first end; and,(b) a housing radial seal member positioned at a location within 50 mmof the first end.

5. A filter cartridge according to any one of characterizations 1-4wherein: (a) the media surrounds and defines a central cartridge axis;and, (b) the media includes a plurality of inner pleats having innerpleat tips extending at an acute angle of no more than 88°, relative toa plane perpendicular to the central axis, in extension toward the firstend.

6. A filter cartridge according to any one of characterizations 1-5wherein: (a) the media surrounds and defines a central cartridge axis;and, (b) the media includes a plurality of inner pleats having innerpleat tips extending at an acute angle within the range of 70°-88°,inclusive, relative to a plane perpendicular to the central axis, inextension toward the first end.

7. A filter cartridge according to any one of characterizations 1-6wherein: (a) the media surrounds and defines a central cartridge axis;and, (b) the media includes a plurality of outer pleats and a pluralityof inner pleats; (i) the inner pleats including a plurality of innerpleat tips extending at a first angle relative to a plane perpendicularto the central axis, in extension from the second end toward the firstend; and, (ii) the outer pleats including a plurality of outer pleatstips extending at a second angle, relative to a plane perpendicular tothe central axis, in extension from the second end toward the first end;(ii) the second angle being greater than the first angle, with respectto a plane perpendicular to the central axis.

8. A filter cartridge according to any one of characterizations 1-7wherein: (a) the media surrounds and defines a central cartridge axis;and, (b) the media includes a plurality of outer pleats having outerpleat tips extending at an angle within the range of 88°-90°, inclusive,relative to a plane perpendicular to the central axis, in extension fromthe second end toward the first end.

9. A filter cartridge comprising: (a) an extension of media having afirst end and a second end; (i) the media surrounding and defining anopen interior; (ii) adjacent the second end, the extension of mediabeing pleated; and, (b) a radially directed housing seal memberpositioned at a location within 50 mm of the first end of the extensionof media; (i) the filter cartridge having a maximum, undistorted, radialwidth dimension, at a location in radial overlap with the media and thehousing radial seal member, of at least 10 mm less than a maximum pleatdepth of the extension of media adjacent the second end of the extensionof media.

10. A filter cartridge comprising: (a) an extension of media surroundingan open interior and having a first end and a second end; (i) the media,adjacent the second end, being pleated and comprising a plurality ofoutwardly directed pleats and a plurality of inwardly directed pleats;and, (ii) each one of the plurality of outwardly directed pleats havinga pleat tip with an outer perimeter tip shape, (iii) an inner perimetertip shape, of each pleat tip of the plurality of inwardly directedpleats, being narrower than the pleat tip shape of each one of theplurality of outwardly directed pleats; (A) the outer pleat tips havingan outer, perimeter, pleat shape at a location adjacent the second endwith a radius of at least 4 mm.

11. A filter cartridge according to any one of characterizations 1-10including: (a) a radially directed housing seal member at a locationwithin 40 mm of the first end of the media.

12. A filter cartridge according to any one of characterizations 1-11including: (a) a radially directed housing seal member positioned within30 mm of the first end of the media.

13. A filter cartridge according to any one of characterizations 1-12including: (a) a radially directed housing seal member positioned at alocation within 20 mm of the first end of the media.

14. A filter cartridge according to any one of characterizations 1-13including: (a) a radially directed housing seal member positioned at alocation within 15 mm of the first end of the media.

15. A filter cartridge according to any one of characterizations 1-14including: (a) a radially outwardly directed housing seal member.

16. A filter cartridge comprising: (a) an extension of media surroundingan open interior and having a first end and a second end; (i) theextension of media being pleated adjacent the second end; and, (b) amedia support; (i) the media including a non-pleated, free, tip sectionadjacent the media first end that extends, axially, in a direction awayfrom the second end, an axial distance of at least 0.5 mm beyond anearest adjacent portion of the media support.

17. A filter cartridge comprising: (a) an extension of pleated mediahaving a first end and a second end; (i) the extension of mediasurrounding an open filter interior; and, (b) a media support includinga first, intermediate, outer pleat spacer positioned between the mediafirst end and the media second end; (i) the first, intermediate, outerpleat spacer defining an outer pleat engagement shape with an outerpleat radius of at least 4 mm; and, (ii) the first, intermediate, outerpleat spacer having radial projections defining inner pleat engagementtips having an outer pleat angle of at least 30°.

18. A filter cartridge comprising: (a) an extension as media havingfirst end and a second end; (i) the extension of media comprising aplurality of pleats adjacent the second end; and, (ii) the mediasurrounding a central axis and defining an open interior; and, (b) aplurality of intermediate outer pleat spacers positioned between themedia first and second ends; (i) axially spaced, adjacent, ones of theplurality of intermediate outer pleat spacers having different amountsof radial projection extension toward the central axis.

19. A filter cartridge comprising: (a) an extension of media having afirst end and a second end; (i) the extension of media comprising aplurality of pleats adjacent the second end; and, (ii) the mediasurrounding and defining an open interior; and, (b) a media supportincluding longitudinal ribs extending along, and secured to, outer pleattips of the media in extension from the second end of the media towardthe first end of the media, along at least 50% of a length of extensionof the outer pleat tips.

20. A filter cartridge comprising: (a) media extending between first andsecond ends and surrounding and defining a central axis and openinterior; and, (b) an end piece adjacent the second end of the media;(i) the end piece defining an outer perimeter of alternating radialoutward projections and radial inward recesses; and, (ii) adjacent onesof the outward projections being spaced by a radial gap of at least 30°.

21. A filter cartridge comprising: (a) media extending between first andsecond ends and surrounding and defining a central axis and an opencentral interior; and (i) the media being pleated adjacent the secondend; and, (b) an end piece adjacent the second end of the media; (i) theend piece defining an outer perimeter of alternating radial outerprojections and radial inward recesses; and, (ii) the end piece radialinward recesses being open, in axial overlap with spaces between outerpleats, by a gap of at least 15 mm in maximum width at a location remotefrom inner pleat tips.

22. A filter cartridge comprising: (a) media extending between first andsecond media ends and surrounding and defining a central axis and anopen central interior; and, (b) an end piece adjacent to, and extendingacross, the second media end; the end piece including: an outer surfacedirected away from the first media end; and, an inner surface directedtoward the first media end; (i) the inner surface of the end piecehaving a central recess therein extending in a direction away from thefirst media end; and, (c) a cushion member positioned in the centralrecess.

23. A filter cartridge comprising: (a) an extension of media having afirst end and a second end and surrounding a central axis and a centralinterior; (b) a media support including an end piece adjacent to thesecond media end; (i) the end piece having a central projection with anaperture therethrough; and, (c) a radially outwardly directed housingradial seal member positioned on, and surrounding, the media support ata location within 50 mm of the first end of the media.

24. A filter cartridge comprising: (a) media extending between first andsecond ends and surrounding and defining a central axis and an opencentral interior; and, (b) an end piece adjacent the second end of themedia; (i) the end piece having an inner surface with a central recesstherein; (ii) the central recess being defined by a projection extendingaway from the media first end having a wall surrounded by, and spacedfrom, the media; and, (iii) the projection having a tip, remote from themedia first end, with an aperture therethrough.

25. A filter cartridge according to any one of characterizations 20-24wherein: (a) the media is pleated adjacent the second end.

26. A filter cartridge according to characterization 25 wherein: (a) themedia, adjacent the second end, includes a plurality of inner pleat tipsextending at an angle of no greater than 88°, relative to a planeperpendicular to the central axis, in extension from the second endtoward the first end.

27. A filter cartridge according to any one of characterizations 2-26wherein: (a) the first end of the media is not pleated.

28. A filter cartridge according to any one of characterizations 1-27wherein: (a) at the second end, the media is pleated with a pleat depthof at least 10 mm.

29. A filter cartridge according to any one of characterizations 1-28wherein: (a) at the second end, the media is pleated with a pleat depthof at least 15 mm.

30. A filter cartridge according to any one of characterizations 1-29wherein: (a) at the second end, the media is pleated with a pleat depthwithin the range of 10 to 40 mm, inclusive.

31. A filter cartridge according to any one of characterizations 1-30wherein: (a) the media includes a plurality of outer pleats adjacent thesecond end; each one of the plurality of outer pleats having an outerpleat tip extending at an acute angle of at least 86°, in extensiontoward the second end, relative to a plane perpendicular to the centralaxis.

32. A filter cartridge according to any one of characterizations 1-31wherein: (a) the media includes a plurality of outer pleats adjacent thesecond end; each one of the plurality of outer pleats having an outerpleat tip extending and an acute angle of at least 87°, in extensiontoward the second end, relative to a plane perpendicular to the centralaxis.

33. A filter cartridge according to any one of characterizations 1-32wherein: (a) the media includes a plurality of outer pleats adjacent thesecond end; each one of the plurality of outer pleats having an outerpleat tip extending at an acute angle within the range of 87-90°,inclusive, in extension toward the second end, relative to a planeperpendicular to the central axis.

34. A filter cartridge according to any one of characterizations 1-33wherein: (a) the media comprises a plurality of inner pleats adjacentthe second end, each one of plurality of inner pleats having an innerpleat tip that extend at an angle of no greater than 87°, relative to aplane perpendicular to the central axis, in extension toward the firstend.

35. A filter cartridge according to any one of characterizations 1-34wherein: (a) the media comprises a plurality of outer pleats with outerpleat tips and a plurality of inner pleats with inner pleat tips; (i)the inner pleat tips extending at a first angle relative to a planeperpendicular to the central axis, in extension from the second endtoward the first end; and, (ii) the outer pleat tips extending at asecond angle, relative to a plane perpendicular to the central axis, inextension from the second end toward the first end; (iii) the firstangle being at least 2° less than the second angle.

36. A filter cartridge according to characterization 35 wherein: (a) thefirst angle is at least 3° less than the second angle.

37. A filter cartridge according to characterization 35 wherein: (a) thefirst angle is at least 4° less than the second angle.

38. A filter cartridge according to any one of characterizations 1-37wherein: (a) the filter cartridge is open at an end adjacent the secondend of the media.

39. A filter cartridge according to any one of characterizations 1-38wherein: (a) the filter cartridge is open at an end adjacent the firstend of the media.

40. A filter cartridge according to any one of characterizations 1-39including: (a) a radially directed housing seal arrangement.

41. A filter cartridge according to characterization 40 wherein: (a) theradially directed housing seal arrangement is a radially outwardlydirected housing seal arrangement.

42. A filter cartridge according to any one of characterizations 1-41including: (a) a radially directed housing seal arrangement comprisingan o-ring.

43. A filter cartridge according to any one of characterizations 1-42including: (a) a media support extending from the second end toward thefirst end of the media.

44. A filter cartridge according to characterization 43 wherein: (a) themedia has an outer surface and an inner surface; (b) the media supporthas first and second ends; and, (c) the media support extends along theouter surface of the media, with no radial support for the media thatextends at least 50% of a distance between the first and second ends ofthe support, that is also positioned projecting radially inwardly fromadjacent portions of the media inner surface.

45. A filter cartridge according to any one of characterizations 43 and44 wherein: (a) the media support includes: an open end within 20 mm ofmedia first end; and, an end piece adjacent the media second end.

46. A filter cartridge according to characterization 45 wherein: (a) theend piece of the media support includes a central aperture therethroughthat is lined with a sealing grommet.

47. A filter cartridge according to any one of characterizations 45 and46 wherein: (a) the end piece of the media support comprises an endpiece having an outer perimeter of alternating radial projections andradial recess; the radial recesses extending radially inwardly at least10 mm from the outermost portions of the radial projections.

48. A filter cartridge according to any one of characterizations 45-47wherein: (a) the end piece of the media support comprises an end piecehaving an outer perimeter of alternating radial projections and radialrecess; the radial recesses extending radially inwardly at least 15 mmfrom the outermost portions of the radial projections.

49. A filter cartridge according to any one of characterizations 45-48wherein: (a) the end piece of the media support comprises an end piecehaving an outer perimeter with a plurality of radial recesses therein;each one of the plurality of radial recesses extending toward a centralaxis by at least 30% of a radial distance between an outermost portionof the closed end of the media support and the central axis.

50. A filter cartridge according to any one of characterizations 45-49wherein: (a) the end piece of the media support comprises an end piecehaving an outer perimeter with a plurality of radial recesses therein;each one of the plurality of radial recess extending toward a centralaxial by at least 35% of a radial distance between an outermost portionof the closed end of the media support and the central axis.

51. A secondary filter cartridge according to any one ofcharacterizations 45-50 wherein: (a) the end piece of the media supportcomprises an end piece having an outer perimeter with a plurality ofradial recesses therein; each one of the plurality of radial recessesextending toward a central axis by at least 40% of a radial distancebetween an outermost portion of the closed end of the media support andthe central axis.

52. A filter cartridge according to any one of characterizations 45-51wherein: (a) the end piece of the media support includes an innersurface with an axially projecting receiver recess therein; (i) theaxially projecting receiver recess projecting axially in a directionaway from a first end of the media.

53. A filter cartridge according to any one of characterizations 45-52wherein: (a) the end piece of the media support includes an outersurface with a central receiving groove therein surrounding an outer,central, projection; (i) the outer, central, projection projecting in adirection axially away from the first end of the media.

54. A filter cartridge according to characterization 53 wherein: (a) theouter, central, projection includes an aperture therethrough, that islined with a sealing grommet.

55. A filter cartridge according to any one of characterizations 53 and54 wherein: (a) the central receiving groove is at least 5 mm deep, inaxial direction toward the first end of the media, from any immediatelysurrounding portion of the closed end of the media support.

56. A filter cartridge according to any one of characterizations 53-55wherein: (a) the outer central projection projects to a tip locatedaxially beyond the second end of the media, from the first end of themedia.

57. A filter cartridge according to any one of characterizations 53-56wherein: (a) the outer central projection projects to a tip at least 5mm from an immediately surrounding portion of the closed end, in adirection axially away from the open end.

58. A filter cartridge according to any one of characterizations 53-57wherein: (a) the outer central projection projects to a tip located atleast 10 mm from an immediately surrounding portion of the end piece ina direction axially away from the open end.

59. A filter cartridge according to any one of characterizations 53-58wherein: (a) the media support includes a plurality of longitudinal ribsextending in a direction from the second end of the media toward thefirst end on the media.

60. A filter cartridge according to characterization 59 wherein: (a)each one of the plurality of longitudinal ribs extends along, andengages, an outer pleat tip of the media.

61. A filter cartridge according to any one of characterizations 53-60wherein: (a) the media support includes at least one intermediate pleatspacer surrounding an outer surface of the media and having radialprojections extending between adjacent media pleats.

62. A filter cartridge according to any one of characterizations 53-61wherein: (a) the media support includes a plurality of intermediatepleat spacers surrounding an outer surface of the media and havingradial projections extending between adjacent media pleats.

63. A filter cartridge according to any one of characterizations 1-62including: (a) a seal support ring surrounding the media within 50 mm ofthe media first end; (i) the seal support ring including an o-ringreceiving groove therein; and, (ii) the seal support ring including aplurality of spaced radial expansion gussets tapering radially inwardlyalong a direction of extension from a location adjacent the o-ringreceiving groove toward the first end of the media.

64. A gas filter assembly comprising: (a) a housing defining an interiorand a gas flow outlet; (i) the housing including a housing base sectionand a removable access cover; (b) a safety filter cartridge according toat least one of claims 1-63 operably and removably positioned within thehousing interior; and, (c) a main filter cartridge comprising mediasurrounding an open filter interior; (i) the main filter cartridge beingoperably and removably positioned within the housing interior with mediaof the safety cartridge projecting into the open filter interior of themain filter cartridge.

65. A gas filter assembly according to characterization 64 wherein: (a)the housing includes a central cartridge support in the housing basesection directed toward the access cover; and, (b) the safety filtercartridge is positioned with the central cartridge support projectinginto an open filter interior of the safety filter cartridge.

66. A gas filter assembly according to characterization 65 wherein: (a)the central cartridge support includes a cartridge support end directedtoward the access cover; (i) the cartridge support end including acentral projection thereon; and, (b) the safety filter cartridgeincludes an inner surface having a receiver recess into which thecentral projection on the central cartridge support extends; (i) aresilient cushion member being provided in the receiver recess of thesafety filter cartridge and around the central projection on the centralcartridge support.

67. A gas filter assembly according to any one of characterizations 65and 66 wherein: (a) the central cartridge support includes a cartridgesupport end directed toward the access cover; (i) the central cartridgesupport end including a central projection thereon; and, (b) the safetyfilter cartridge including an end directed toward the access cover witha projection having a tip with an aperture therethrough; (i) the centralprojection on the central cartridge support projecting completelythrough the aperture in the tip of the projection in the safety filtercartridge.

68. A gas filter assembly according to any one of characterizations66-67 including: (a) a seal member on the safety filter cartridge inreleasable sealing engagement around the central projection on thecentral cartridge support.

69. A gas filter assembly according to characterization 68 wherein: (a)the central projection on the central cartridge support includes a tipand a neck section; (i) the neck section having a narrowercross-sectional dimension than a dimension of the central projection onthe central cartridge support, adjacent the tip.

70. A gas filter assembly according to characterization 68 wherein: (a)an interference fit is provided between the tip of the centralprojection on the central cartridge support, and the safety filtercartridge, by the tip and the neck section.

71. A gas filter assembly according to any one of characterizations64-70 wherein: (a) the housing includes a seal flange surrounding asafety filter cartridge end receiver recess; and, (b) the safety filtercartridge is positioned with the media first end projecting into thesafety filter cartridge end receiver recess.

72. A gas filter assembly according to characterization 71 wherein: (a)the safety filter cartridge end receiver recess has a maximum radialwidth of no greater than 15 mm; and, (b) the safety filter cartridgeincludes media having a pleat depth, adjacent a second end, of greaterthan 15 mm.

73. A gas filter assembly according to any one of characterizations 71and 72 wherein: (a) at the media first end, the safety filter cartridgeis non-pleated.

74. A gas filter assembly according to any one of characterizations71-73 wherein: (a) the media first end, of the safety filter cartridge,is a free end having a tip of extension of at least 0.5 mm with no endcap thereon, and no media support structure, of the safety filtercartridge, positioned radially thereagainst.

75. A gas filter assembly according to any one of characterizations71-74 wherein: (a) the safety filter cartridge end receiver recess ispositioned between the seal flange and a base end of a central cartridgesupport; (i) the central cartridge support being separate from thesafety filter cartridge and being positioned in the housing at alocation projecting toward the access cover.

76. A gas filter assembly according to any one of characterizations64-75 wherein: (a) the media of the main filter cartridge has a firstend and a second end; (i) the media of the main filter cartridge havingan internal perimeter that decreases in cross-sectional dimension inextension from the first end to the second end.

77. A gas filter assembly according to characterization 76 wherein: (a)the main filter cartridge includes a first end piece adjacent the firstend and a second end piece adjacent the second end; (i) the first endpiece being open; and, (ii) the second end piece being closed andincluding a central projection thereon projecting from the second end ofthe media toward the first end of the media at least 15% of a distancefrom the second end of the media toward the first end of the media.

78. A gas filter assembly according to any one of characterizations64-77 wherein: (a) the main filter cartridge includes a first end pieceadjacent the first end and a second end piece adjacent the second end;(i) the first end piece being open; and, (ii) the second end piece beingclosed and including a central projection thereon projecting from thesecond end of the media toward the first end of the media at least 20%of a distance from the second end of the media toward the first end ofthe media.

79. A gas filter assembly according to any one of characterizations76-78 wherein: (a) the safety filter cartridge projects into the openfilter interior of the main filter cartridge to a location no more than90% of a distance from the first end of the main filter cartridge mediato the second end of the main filter cartridge media.

80. A gas filter assembly according to any one of characterizations76-79 wherein: (a) the safety filter cartridge projects into the openfilter interior of the main filter cartridge to a location no more than85% of a distance from the first end of the main filter cartridge mediato the second end of the main filter cartridge media.

81. A gas filter cartridge according to any one of characterizations76-80 wherein: (a) at a location around the second end of the media ofthe safety cartridge, a clearance between the main filter cartridge andthe safety cartridge is no more than 8 mm.

82. A gas filter assembly according to any one of characterizations64-81 wherein: (a) the housing includes a central cartridge support, inthe housing base section, directed toward the access cover; (b) thesafety filter cartridge is positioned with the central cartridge supportprojecting into an open filter interior of the safety filter cartridge;(c) the safety filter cartridge includes an end, directed toward theaccess cover, having a recess into which the central projection on thecartridge support extends; (i) the receiver recess in the safety filtercartridge being defined by a projection directed toward the accesscover; (d) a resilient cushion member being provided in the receiverrecess of the safety filter cartridge and around the central projectionon the central cartridge support; and, (e) the main filter cartridgeincludes a closed end piece having an inner surface with a receiverrecess therein; (i) the central projection on the cartridge support, andthe projection on the safety filter cartridge defining the receiverrecess in the safety filter cartridge, projecting into the receiverrecess in the inner surface of the closed end piece of the main filtercartridge.

83. A gas filter assembly according to any one of characterizations64-82 wherein: (a) the housing includes a central cartridge support inthe housing base section directed toward the access cover; (b) thesafety filter cartridge is positioned with the central cartridge supportprojecting into an open filter interior of the safety filter cartridge;(c) a resilient cushion member is provided in the receiver recess of thesafety filter cartridge around the central projection on the centralcartridge support; (d) the safety filter cartridge includes an enddirected toward the access cover having an outer surface with a receivergroove surrounding a central projection; and, (e) the main filtercartridge includes a closed end piece having an inner surface with aprojection extending into the receiver groove on the outer surface ofthe safety cartridge end.

84. A gas filter assembly comprising: (a) a housing defining an interiorand a gas flow outlet; (i) the housing including a housing base sectionand a removable access cover; (ii) the housing including a centralcartridge support in the housing base section directed toward the accesscover; (b) a safety filter cartridge positioned over the centralcartridge support; the safety filter comprising media having first andsecond ends, surrounding a central axis and defining an open interior;(i) at the first end, the media having no pleat greater than 3 mm indepth; and, (ii) at the second end, the media comprising a plurality ofpleats each having a pleat depth of at least 10 mm; (c) a main filtercartridge comprising media surrounding a central axis and defining anopen interior; (i) the media being pleated in extension between firstand second ends; (ii) the media tapering inwardly in extension from thefirst end toward the second end; (iii) the main filter cartridgeincluding a first, open, end piece on the media first end; (A) aradially inwardly directed housing seal being positioned on the firstend piece; and, (iv) the main filter cartridge including a closed endpiece on the media second end; (A) the closed end piece including acentral projection extending toward the first end of the media to alocation at least 15% of a distance between the media second end and themedia first end.

85. A gas filter assembly according to characterization 84 wherein: (a)the closed end piece including a central projection extending toward thefirst end of the media to a location at least 20% of a distance betweenthe media second end and the media first end.

86. A gas filter assembly according to any one of characterizations 84and 85 wherein: (a) the closed end piece including a central projectionextending toward the first end of the media to a location at least 20%,in some instances at least 24% of a distance between the media secondend and the media first end.

87. A gas filter assembly according to any one of claims 84-86 wherein:(a) the safety filter cartridge is in accord with any one ofcharacterizations 1-63.

88. A gas filter assembly according to any one of characterizations 1-87wherein: (a) the assembly is in accord with any one of claims 64-83.

89. A housing for a gas filter assembly; the housing: (a) defining aninterior and a gas flow outlet; (i) the housing including a housing basesection and a removable access cover; (b) the housing including acentral cartridge support in the housing base section directed towardthe access cover; and, (c) the central cartridge support includes acartridge support end directed toward the access cover having a centralprojection with an end tip and a neck section; (i) the neck sectionhaving a narrower cross-sectional dimension than a dimension of thecentral projection on the central cartridge support, adjacent the endtip.

90. A housing according to characterization 89 including: (a) a sealflange surrounding an end of the central cartridge support defining asafety filter cartridge and receiver recess having a maximum radialwidth of no greater than 25 mm.

91. An air filter cartridge comprising: (a) media surrounding a centralaxis and defining an open interior; (i) the media being pleated inextension between first and second ends; (ii) the media taperinginwardly in extension from the first end toward the second end; (iii)the main filter cartridge including a first, open, end piece on themedia first end; (b) the main filter cartridge including a closed endpiece on the media second end; (i) the closed end piece including acentral section extending toward the first end of the media to alocation at least 15%, typically at least 20%, often at least 24%, of adistance between the media second end and the media first end; and, (ii)the central section including a central projection thereon directed awayfrom the first end piece and terminating at and end remote from themedia first end at a location that is spaced, in a direction toward themedia first end, from the media second end at least 15% of a distancefrom the media second end to the media first end; (A) the centralprojection defining a receiver recess on an inner surface thereof.

92. An air filter cartridge comprising: (a) media surrounding a centralaxis and defining an open interior; (i) the media being pleated inextension between first and second ends; (ii) the media taperinginwardly in extension from the first end toward the second end; (iii)the main filter cartridge including a first, open, end piece on themedia first end; (b) the main filter cartridge including a closed endpiece on the media second end; (i) the closed end piece including acentral section extending toward the first end of the media to alocation at least 20% of a distance between the media second end and themedia first end; and, (ii) the central section including a centralprojection thereon directed away from the first end piece andterminating at and end remote from the media first end; (A) the centralsection defining a receiver recess on an inner surface thereof and, (B)the central section including a plurality of spaced centering finsthereon spaced from the central projection and directed toward thecentral projection and a cartridge central axis.

93. An air filter cartridge according to claim 24 wherein: (a) thecentral location terminates at a location that is spaced, in a directiontoward the media first end, from the media second end at least 15% of adistance from the media second end to the media first end.

The principles, techniques, and features described herein can be appliedin a variety of systems, and there is no requirement that all of theadvantageous features identified be incorporated in an assembly, systemor component to obtain some benefit according to the present disclosure.In addition, the dimensions characterizing an example system are meantto indicate a usable construction, and variations from them arepossible.

What is claimed is:
 1. A filter cartridge comprising: (a) an extensionof media surrounding an open interior and having a first end and asecond end; and, (b) an end piece adjacent the second end of the media;the end piece including: (i) a central region having a centralprojection extending in a direction away from the first end; (ii) anouter surface directed away from the first media end; (iii) an innersurface directed toward the first media end having a central recesstherein extending in a direction away from the first media end andsurrounded by the central projection; and, (iv) a resilient grommethaving a portion positioned on the central projection and in the centralrecess to surround a space sized to receive a projection therein whenthe filter cartridge is installed for use.
 2. A filter cartridgeaccording to claim 1 wherein: (a) the extension of media surrounds acentral axis; (i) the media being pleated adjacent the second end anddefining a plurality of inner pleat tips extending at an acute angle,relative to a plane perpendicular to the central axis, of no greaterthan 89°, in extension toward the first end; and, (ii) the media beingnon-pleated at the first end.
 3. A filter cartridge according to claim 2including: (a) a housing radial seal member positioned at a locationwithin 50 mm of the first end.
 4. A filter cartridge according to claim1 wherein: (a) the media surrounds and defines a central cartridge axis;and, (b) the media includes a plurality of inner pleats having innerpleat tips extending at an acute angle within the range of 70°-88°,inclusive, relative to a plane perpendicular to the central axis, inextension toward the first end.
 5. A filter cartridge according to claim4 wherein: (a) the media includes a plurality of outer pleats havingouter pleat tips extending at an angle within the range of 88°-90°,inclusive, relative to a plane perpendicular to the central axis, inextension from the second end toward the first end.
 6. A filtercartridge according to claim 1: (a) a radially directed housing sealmember positioned at a location within 50 mm of the first end of theextension of media; (i) the filter cartridge having a maximum,undistorted, radial width dimension, at a location in radial overlapwith the media and the housing radial seal member, of at least 10 mmless than a maximum pleat depth of the extension of media adjacent thesecond end of the extension of media.
 7. A filter cartridge according toclaim 1 including: (a) a radially directed housing seal member at alocation within 40 mm of the first end of the media.
 8. A filtercartridge according to claim 7 therein: (a) the radially directedhousing seal member is positioned at a location within 15 mm of thefirst end of the media.
 9. A filter cartridge according to claim 8including: (a) the housing seal member is a radially outwardly directedhousing seal member.
 10. A filter cartridge according to claim 1including: (a) a media support; (i) the media including a non-pleated,free, tip section adjacent the media first end that extends, axially, ina direction away from the second end, an axial distance of at least 0.5mm beyond a nearest adjacent portion of the media support.
 11. A filtercartridge according to claim 1 including: (a) a plurality ofintermediate outer pleat spacers positioned between the media first andsecond ends; (i) axially spaced, adjacent, ones of the plurality ofintermediate outer pleat spacers having different amounts of radialprojection extension toward a central axis.
 12. A filter cartridgeaccording to claim 1 including: (a) a media support having longitudinalribs extending along, and secured to, outer pleat tips of the media inextension from the second end of the media toward the first end of themedia, along at least 50% of a length of extension of the outer pleattips.
 13. A filter cartridge according to claim 1 wherein: (a) at thefirst end, the media has no pleat greater than 3 mm in depth; and, (b)at the second end, the media comprises a plurality of pleats each havinga pleat depth of at least 10 mm.
 14. A filter cartridge according toclaim 1 wherein: (a) the grommet includes a central bore completelytherethrough.
 15. A filter cartridge according to claim 1 wherein: (a)the central projection extends in a direction away from the first endhas inner surface with a frusto-conical shape.
 16. A filter cartridgeaccording to claim 1 wherein: (a) the outer surface of the end pieceadjacent the second end of the media includes an outer receiving groovetherein.
 17. A filter cartridge according to claim 16 wherein: (a) theouter receiving groove is at least 5 mm deep in axial extension fromimmediately adjacent portions of the end piece adjacent the second endof the media.
 18. A filter cartridge according to claim 16 wherein: (a)the outer receiving groove is at least 8 mm deep in axial extension fromimmediately adjacent portions of the end piece adjacent the second endof the media.
 19. A filter cartridge according to claim 16 wherein: (a)the outer receiving groove is 8-20 mm, inclusive, deep in axialextension from immediately adjacent portions of the end piece adjacentthe second end of the media.
 20. A filter cartridge according to claim16 wherein: (a) the outer receiving groove is at least 5 mm wide.
 21. Afilter cartridge according to claim 16 wherein: (a) the outer receivinggroove has a width of 6-30 mm, inclusive.